diff --git a/src/utils/util/resolver-pipeline/oscal-profile-resolve-merge.xsl b/src/utils/util/resolver-pipeline/oscal-profile-resolve-merge.xsl
index d6464f5506..89099f6f9f 100644
--- a/src/utils/util/resolver-pipeline/oscal-profile-resolve-merge.xsl
+++ b/src/utils/util/resolver-pipeline/oscal-profile-resolve-merge.xsl
@@ -1,6 +1,7 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<xsl:stylesheet version="2.0"
+<xsl:stylesheet version="3.0"
     xmlns="http://csrc.nist.gov/ns/oscal/1.0"
+    xmlns:mh="http://csrc.nist.gov/ns/message"
     xmlns:o="http://csrc.nist.gov/ns/oscal/1.0"
     xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
     xmlns:xs="http://www.w3.org/2001/XMLSchema"
@@ -9,8 +10,10 @@
     exclude-result-prefixes="xs math o opr"
     xpath-default-namespace="http://csrc.nist.gov/ns/oscal/1.0" >
 
-    <!-- XSLT 2.0 so as to validate against XSLT 3.0 constructs -->
+    <xsl:import href="message-handler.xsl"/>
 
+    <xsl:variable name="in_xspec" as="xs:boolean" select="false()"/>
+    <xsl:variable name="true-content" as="xs:string+" select="('true','1')"/>
 
     <xsl:template match="* | @*" mode="#all">
         <xsl:copy copy-namespaces="no">
@@ -25,34 +28,43 @@
             templates not this one. -->
     </xsl:template>
 
-    <xsl:template match="catalog" priority="2">
+    <!-- If there is no selection and no merge (i.e., we don't reach one of
+        the higher-priority templates that match catalog), pass the catalog
+        through unchanged. -->
+    <xsl:template match="catalog" priority="2" as="element(catalog)">
         <xsl:copy-of select="."/>
     </xsl:template>
 
-    <xsl:template match="catalog[exists(selection)]" priority="10">
+    <!-- If there is a selection but neither merge/as-is nor merge/custom,
+        use flat structuring. -->
+    <xsl:template match="catalog[exists(selection)]" priority="10" as="element(catalog)">
         <catalog>
             <xsl:apply-templates select="@*"/>
             <xsl:apply-templates select="metadata"/>
             <xsl:apply-templates select="selection"/>
             <xsl:apply-templates select="modify"/>
-            <xsl:for-each-group select="back-matter/* | selection/back-matter/*" group-by="true()">
+            <xsl:where-populated>
                 <back-matter>
-                    <xsl:copy-of select="current-group()"/>
+                    <xsl:sequence select="back-matter/* | selection/back-matter/*"/>
                 </back-matter>
-            </xsl:for-each-group>
+            </xsl:where-populated>
         </catalog>
     </xsl:template>
 
-    <xsl:template priority="12" match="catalog[merge/as-is=('true','1')]">
+    <!-- If there is a merge/as-is directive, we go down that branch.
+        If there is also a merge/custom directive, we apply the
+        higher-priority template instead of this one. -->
+    <xsl:template match="catalog[merge/as-is=$true-content]" priority="12" as="element(catalog)">
+        <xsl:call-template name="detect-multiple-structuring-directives"/>
         <catalog>
             <xsl:apply-templates select="@*"/>
             <xsl:apply-templates select="metadata"/>
             <xsl:variable name="merged-selections">
-            <xsl:call-template name="o:merge-groups-as-is">
-                <xsl:with-param name="merging" select="selection"/>
-            </xsl:call-template>
+                <xsl:call-template name="o:merge-groups-as-is">
+                    <xsl:with-param name="merging" select="selection"/>
+                </xsl:call-template>
             </xsl:variable>
-            <!-- not copying the selection elements only their contents -->
+            <!-- not copying the selection elements, only their contents -->
             <xsl:for-each select="$merged-selections/selection">
                 <xsl:sequence select="* except back-matter"/>
             </xsl:for-each>
@@ -64,7 +76,8 @@
 
 
     <!-- If there is a merge/custom directive, we go down that branch. -->
-    <xsl:template priority="13" match="catalog[exists(merge/custom)]">
+    <xsl:template match="catalog[exists(merge/custom)]" priority="13" as="element(catalog)">
+        <xsl:call-template name="detect-multiple-structuring-directives"/>
         <catalog>
             <xsl:apply-templates select="@*"/>
             <xsl:apply-templates select="metadata"/>
@@ -77,18 +90,34 @@
         </catalog>
     </xsl:template>
 
-    <xsl:template name="combine-back-matter">
-        <xsl:variable name="here" select="self::catalog"/>
-        <xsl:for-each-group select="back-matter/* | selection/back-matter/*" group-by="true()">
+    <xsl:template name="detect-multiple-structuring-directives" as="empty-sequence()">
+        <xsl:context-item as="element(catalog)" use="required"/>
+        <xsl:variable name="flat" as="element(flat)*" select="merge/flat[.=$true-content]"/>
+        <xsl:variable name="as-is" as="element(as-is)*" select="merge/as-is[.=$true-content]"/>
+        <xsl:variable name="custom" as="element(custom)*" select="merge/custom"/>
+        <xsl:if test="count($flat) + count($as-is) + count($custom) gt 1">
+            <xsl:call-template name="mh:message-handler">
+                <xsl:with-param name="text">Found multiple structuring directives. Choose at most one from: flat (default), as-is, custom.</xsl:with-param>
+                <xsl:with-param name="message-type">Error</xsl:with-param>
+                <xsl:with-param name="terminate" select="true()"/>
+            </xsl:call-template>
+        </xsl:if>
+    </xsl:template>
+
+    <xsl:template name="combine-back-matter" as="element(back-matter)?">
+        <xsl:context-item as="element(catalog)" use="required"/>
+        <xsl:where-populated>
             <back-matter>
                 <!-- Using combination logic on back matter elements. -->
-                <xsl:for-each-group select="current-group()" group-by="(@opr:id,@id,generate-id())[1]">
+                <xsl:for-each-group select="back-matter/* | selection/back-matter/*" group-by="(@opr:id,@uuid,generate-id())[1]">
                     <xsl:call-template name="combine-elements">
-                        <xsl:with-param name="who" select="current-group()"/>
+                        <!-- Take last one in group because of spec
+                            requirement id="req-backmatter-dupe". -->
+                        <xsl:with-param name="who" select="current-group()[last()]" as="element(resource)"/>
                     </xsl:call-template>
                 </xsl:for-each-group>
             </back-matter>
-        </xsl:for-each-group>
+        </xsl:where-populated>
     </xsl:template>
 
     <xsl:template match="selection">
@@ -96,64 +125,58 @@
         <xsl:apply-templates select="control | .//group/control"/>
     </xsl:template>
 
-    <xsl:key name="control-by-id" match="control" use="@id"/>
-
-    <xsl:template match="node() | @*" mode="o:custom-merge">
-        <xsl:copy>
-            <xsl:apply-templates mode="#current" select="node() | @*"/>
-        </xsl:copy>
-    </xsl:template>
-
+    <!-- Process children but do not copy <custom> tags themselves. -->
     <xsl:template match="custom" mode="o:custom-merge">
         <xsl:apply-templates mode="#current"/>
     </xsl:template>
 
+    <!-- Apply the requested ordering.
+        Creating the properly combined sequence of inserted controls
+        is in downstream template. -->
     <xsl:template match="insert-controls" mode="o:custom-merge">
-        <xsl:variable name="inserted-controls">
+        <xsl:variable name="inserted-controls" as="element()*">
             <xsl:apply-templates mode="#current"/>
         </xsl:variable>
         <xsl:variable name="keep-order" select="not(@order = ('descending','ascending'))" as="xs:boolean"/>
         <xsl:variable name="sort-order" select="@order[.='descending'],'ascending'"/>
         <!-- Setting sort-key to '1' sorts into given order -->
-        <xsl:perform-sort  select="$inserted-controls">
-                <xsl:sort select="if ($keep-order) then '1' else @control-id"/>
+        <xsl:perform-sort select="$inserted-controls">
+            <xsl:sort select="if ($keep-order) then '1' else @id" 
+                order="{$sort-order[1]}"/>
         </xsl:perform-sort>
     </xsl:template>
 
-    <xsl:template match="include-controls" mode="o:custom-merge">
-        <xsl:variable name="match-patterns" select="matching/@pattern"/>
-        <xsl:call-template name="combine-elements">
-            <xsl:with-param name="who" select="key('control-by-id', with-id),
-                /*/selection//control[some $p in ($match-patterns) satisfies (matches(@id,o:glob-as-regex(string($p))))]"/>
-        </xsl:call-template>
-    </xsl:template>
+    <xsl:include href="select-or-custom-merge.xsl"/>
 
-    <xsl:template match="include-all" mode="o:custom-merge">
-        <xsl:variable name="match-patterns" select="matching/@pattern"/>
+    <!-- Combine selected controls.
+        Creating the sequence of controls ($who) is in code shared with
+        selection phase. -->
+    <xsl:template match="include-all | include-controls" mode="o:custom-merge">
+        <xsl:variable name="who" as="element(o:control)*">
+            <xsl:apply-templates select="ancestor::*[last()]//selection" mode="o:select">
+                <xsl:with-param tunnel="yes" name="import-instruction" select="ancestor::insert-controls"/>
+            </xsl:apply-templates>
+        </xsl:variable>
         <xsl:call-template name="combine-elements">
-            <xsl:with-param name="who" select="//control"/>
+            <xsl:with-param name="who" select="$who"/>
         </xsl:call-template>
     </xsl:template>
 
-    <xsl:include href="oscal-profile-resolve-functions.xsl"/>
+    <!-- No-op because exclusion logic is handled in the code shared with
+            selection phase. -->
+    <xsl:template match="exclude-controls" mode="o:custom-merge"/>
 
-    <!--<xsl:template match="with-id">
-        <xsl:call-template name="combine-elements">
-            <xsl:with-param name="who" select="key('control-by-id', @control-id)"/>
-        </xsl:call-template>
+    <!-- In o:select mode, process children of selection or group to reach
+        controls, which are handled in select-or-custom-merge.xsl. -->
+    <xsl:template match="selection | selection//group" mode="o:select">
+        <xsl:apply-templates select="group | control" mode="#current"/>
     </xsl:template>
 
-    <xsl:template match="matching" mode="o:custom-merge">
-        <xsl:variable name="p" select="@pattern"/>
-        <xsl:call-template name="combine-elements">
-            <xsl:with-param name="who" select="/*/selection//control[matches(@id,$p)]"/>
-        </xsl:call-template>
-    </xsl:template>-->
-
     <xsl:template name="o:merge-groups-as-is">
-        <xsl:param name="merging" select="()"/>
+        <xsl:context-item as="element()" use="optional"/>
+        <xsl:param name="merging" select="()" as="element()*"/>
         <xsl:for-each-group select="$merging" group-by="(@uuid,@opr:id,@id,generate-id())[1]">
-            <xsl:variable name="merged" select="current-group()"/>
+            <xsl:variable name="merged" select="current-group()" as="element()+"/>
             <xsl:for-each select="$merged[1]">
                 <xsl:copy copy-namespaces="no">
                     <xsl:apply-templates select="$merged/@*"/>
@@ -177,6 +200,7 @@
     </xsl:template>
 
     <xsl:template name="combine-elements">
+        <xsl:context-item as="element()" use="required"/>
         <xsl:param name="who" as="element()*"/>
         <xsl:apply-templates select="ancestor-or-self::catalog" mode="o:combine-elements">
             <xsl:with-param name="elements" select="$who"/>
@@ -194,15 +218,26 @@
         <!-- All the elements coming in have the same name but different opr:id
              we operate on controls and parameters (not groups or group contents otherwise) -->
         <!-- further, we assume all controls or all parameters -->
-        <xsl:if test="$elements/name() != $elements/name()">
-            <opr:error> ... elements of different types combining ...</opr:error></xsl:if>
+        <xsl:variable name="uri-qualified-name" as="function(*)"
+            select="function($node as element()) as xs:string {
+                'Q{' || namespace-uri($node) || '}' || local-name($node)
+            }"/>
+        <xsl:variable name="element-names" as="xs:string*"
+            select="$elements ! $uri-qualified-name(.)"/>
+        <xsl:if test="$element-names != $element-names">
+            <!-- If we get here for a valid profile, it is an XSLT bug rather than a user error. -->
+            <xsl:call-template name="mh:message-handler">
+                <xsl:with-param name="text">Combining elements of different types is not supported.</xsl:with-param>
+                <xsl:with-param name="message-type">Error</xsl:with-param>
+                <xsl:with-param name="terminate" select="$in_xspec"/>
+            </xsl:call-template>
+        </xsl:if>
         <xsl:for-each-group select="$elements" group-by="(@opr:id,@id,generate-id())[1]">
-            <xsl:variable name="merged" select="current-group()"/>
+            <xsl:variable name="merged" select="current-group()" as="element()+"/>
             <xsl:for-each select="$merged[1]">
                 <xsl:copy copy-namespaces="no">
                     <xsl:apply-templates select="$merged/@*"/>
                     <xsl:apply-templates select="$merged/*"/>
-
                 </xsl:copy>
             </xsl:for-each>
         </xsl:for-each-group>
@@ -219,7 +254,7 @@
         <xsl:apply-templates select="$elements"/>
     </xsl:template>
 
-<!-- Scrubbing opr:id values on the way out - we don't need them. -->
+    <!-- Scrubbing opr:id values on the way out - we don't need them. -->
     <xsl:template match="@opr:id"/>
 
 </xsl:stylesheet>
diff --git a/src/utils/util/resolver-pipeline/oscal-profile-resolve-select.xsl b/src/utils/util/resolver-pipeline/oscal-profile-resolve-select.xsl
index d8ca35000a..52ea10a3b2 100644
--- a/src/utils/util/resolver-pipeline/oscal-profile-resolve-select.xsl
+++ b/src/utils/util/resolver-pipeline/oscal-profile-resolve-select.xsl
@@ -95,7 +95,7 @@
         <xsl:variable name="linked-xml" select="child::rlink[ends-with(@href,'.xml') or matches(@media-type,'xml')][1]"/>
         <xsl:choose>
             <xsl:when test="exists($linked-xml)">
-        <xsl:apply-templates mode="o:select" select="o:resource-or-error($linked-xml/@href)"/>
+                <xsl:apply-templates mode="o:select" select="o:resource-or-error($linked-xml/@href)"/>
             </xsl:when>
             <xsl:otherwise>
                 <xsl:message terminate="yes"
@@ -126,30 +126,6 @@
         </xsl:copy>
     </xsl:template>
 
-    <xsl:template name="add-process-id" as="attribute(opr:id)">
-        <xsl:param name="context" select="." as="element()"/>
-        <xsl:attribute name="opr:id" namespace="http://csrc.nist.gov/ns/oscal/profile-resolution">
-            <xsl:value-of
-                select="concat(opr:catalog-identifier($context/root()/o:catalog), '#', $context/(@id, generate-id())[1])"/>
-        </xsl:attribute>
-    </xsl:template>
-
-    <xsl:function name="opr:catalog-identifier" as="xs:string">
-        <xsl:param name="catalog" as="element(o:catalog)"/>
-        <xsl:sequence select="$catalog/(@uuid,document-uri(root(.)))[1]"/>
-    </xsl:function>
-
-    <!-- A control is included if it is selected by the provided import instruction -->
-    <xsl:template match="control" mode="o:select" as="element(o:control)?">
-        <xsl:param name="import-instruction" tunnel="yes" required="yes"/>
-        <xsl:if test="o:selects($import-instruction,.)">
-            <xsl:copy copy-namespaces="no">
-                <xsl:call-template name="add-process-id"/>
-                <xsl:apply-templates mode="#current" select="node() | @*"/>
-            </xsl:copy>
-        </xsl:if>
-    </xsl:template>
-
     <!-- Parameters are always passed through until later stages. -->
     <xsl:template match="param" mode="o:select">
         <xsl:copy copy-namespaces="no">
@@ -170,58 +146,6 @@
         </xsl:if>
     </xsl:template>-->
 
-    <!-- Function o:selects($importing,$candidate) returns a true or false
-         depending on whether the import calls the candidate control  -->
-
-<!-- @with-child-controls='yes' is recursive - given on a control it brings all control descendants, not only children   -->
-    <xsl:function name="o:selects" as="xs:boolean">
-        <xsl:param name="importing" as="element(o:import)"/>
-        <xsl:param name="candidate" as="element(o:control)"/>
-        <xsl:variable name="include-reasons" as="xs:boolean+">
-<!-- we are not optimizing for performance here; nothing is done to prevent all checks even if the first passes -->
-            <!--<xsl:sequence select="empty($importing/include)"/>-->
-            <xsl:sequence select="exists($importing/include-all)"/>
-            <xsl:sequence select="some $c in ($importing/include-controls/with-id)
-                                  satisfies ($c = $candidate/@id)"/>
-            <xsl:sequence select="some $c in ($importing/include-controls[o:calls-parents(.)]/with-id)
-                satisfies ($c = $candidate/descendant::control/@id)"/>
-            <xsl:sequence select="some $c in ($importing/include-controls[o:calls-children(.)]/with-id)
-                satisfies ($c = $candidate/ancestor::control/@id)"/>
-            <xsl:sequence select="some $m in ($importing/include-controls/matching[@pattern != ''])
-                                  satisfies (matches($candidate/@id,$m/@pattern/o:glob-as-regex(string(.)) ))"/>
-            <xsl:sequence select="some $m in ($importing/include-controls[o:calls-parents(.)]/matching[@pattern != '']), $a in $candidate/descendant::control 
-                satisfies (matches($a/@id,$m/@pattern/o:glob-as-regex(string(.))))"/>
-            <xsl:sequence select="some $m in ($importing/include-controls[o:calls-children(.)]/matching[@pattern != '']), $a in $candidate/ancestor::control 
-                satisfies (matches($a/@id,$m/@pattern/o:glob-as-regex(string(.))))"/>
-        </xsl:variable>
-        <xsl:variable name="exclude-reasons" as="xs:boolean+">
-            <xsl:sequence select="exists($candidate/parent::control) and $importing/include-all/@with-child-controls='no'"/>
-            <xsl:sequence select="some $c in ($importing/exclude-controls/with-id) satisfies ($c = $candidate/@id)"/>
-            <xsl:sequence select="some $c in ($importing/exclude-controls[o:calls-parents(.)]/with-id)
-                satisfies ($c = $candidate/descendant::control/@id)"/>
-            <xsl:sequence select="some $c in ($importing/exclude-controls[o:calls-children(.)]/with-id)
-                satisfies ($c = $candidate/ancestor::control/@id)"/>
-            <xsl:sequence select="some $m in ($importing/exclude-controls/matching[@pattern != ''])
-                satisfies (matches($candidate/@id,$m/@pattern/o:glob-as-regex(string(.))))"/>
-            <xsl:sequence select="some $m in ($importing/exclude-controls[o:calls-parents(.)]/matching[@pattern != '']), $a in $candidate/descendant::control
-                satisfies (matches($a/@id,$m/@pattern/o:glob-as-regex(string(.))))"/>
-            <xsl:sequence select="some $m in ($importing/exclude-controls[o:calls-children(.)]/matching[@pattern != '']), $a in $candidate/ancestor::control
-                satisfies (matches($a/@id,$m/@pattern/o:glob-as-regex(string(.))))"/>
-        </xsl:variable>
-        <!-- predicate [.] filters reasons as booleans -->
-        <xsl:sequence select="exists($include-reasons[.]) and empty($exclude-reasons[.])"/>
-    </xsl:function>
-
-    <xsl:function name="o:calls-children" as="xs:boolean">
-        <xsl:param name="caller" as="element()"/>
-        <xsl:sequence select="$caller/@with-child-controls='yes'"/>
-    </xsl:function>
-
-    <xsl:function name="o:calls-parents" as="xs:boolean">
-        <xsl:param name="caller" as="element()"/>
-        <xsl:sequence select="not($caller/@with-parent-controls='no')"/>
-    </xsl:function>
-
     <!-- Returns a document when found, a fatal error when not. -->
     <xsl:function name="o:resource-or-error" as="document-node()">
         <xsl:param name="href" as="attribute(href)"/>
@@ -232,7 +156,7 @@
         <xsl:sequence select="document($resolved-href)"/>
     </xsl:function>
 
-    <xsl:include href="oscal-profile-resolve-functions.xsl"/>
+    <xsl:include href="select-or-custom-merge.xsl"/>
 
     <xsl:function name="o:resolve-profile">
         <xsl:param name="profile" as="element(profile)"/>
diff --git a/src/utils/util/resolver-pipeline/select-or-custom-merge.xsl b/src/utils/util/resolver-pipeline/select-or-custom-merge.xsl
new file mode 100644
index 0000000000..62c652ffd3
--- /dev/null
+++ b/src/utils/util/resolver-pipeline/select-or-custom-merge.xsl
@@ -0,0 +1,97 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<xsl:stylesheet version="3.0"
+    xmlns="http://csrc.nist.gov/ns/oscal/1.0"
+    xmlns:o="http://csrc.nist.gov/ns/oscal/1.0"
+    xmlns:opr="http://csrc.nist.gov/ns/oscal/profile-resolution"
+    xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
+    xmlns:xs="http://www.w3.org/2001/XMLSchema"
+    xmlns:math="http://www.w3.org/2005/xpath-functions/math"
+    exclude-result-prefixes="xs math o"
+    xpath-default-namespace="http://csrc.nist.gov/ns/oscal/1.0">
+
+    <xsl:include href="oscal-profile-resolve-functions.xsl"/>
+
+    <!-- A control is included if it is selected by the provided import instruction -->
+    <xsl:template match="control" mode="o:select" as="element(o:control)?">
+        <xsl:param name="import-instruction" tunnel="yes" required="yes"/>
+        <xsl:choose>
+            <xsl:when test="o:selects($import-instruction,.)">
+                <xsl:copy copy-namespaces="no">
+                    <xsl:call-template name="add-process-id"/>
+                    <xsl:apply-templates mode="#current" select="node() | @*"/>
+                </xsl:copy>
+           </xsl:when>
+           <xsl:otherwise>
+               <!-- Visit child controls in case they are selected using
+                   with-parent-controls="no". -->
+               <xsl:apply-templates mode="#current" select="control"/>
+           </xsl:otherwise>
+        </xsl:choose>
+    </xsl:template>
+
+    <xsl:template name="add-process-id" as="attribute(opr:id)">
+        <xsl:param name="context" select="." as="element()"/>
+        <xsl:attribute name="opr:id" namespace="http://csrc.nist.gov/ns/oscal/profile-resolution">
+            <xsl:value-of
+                select="concat(opr:catalog-identifier($context/root()/o:catalog), '#', $context/(@id, generate-id())[1])"/>
+        </xsl:attribute>
+    </xsl:template>
+
+    <!-- Function o:selects($importing,$candidate) returns a true or false
+         depending on whether the import calls the candidate control  -->
+    
+    <!-- @with-child-controls='yes' is recursive - given on a control it brings all control descendants, not only children   -->
+    <xsl:function name="o:selects" as="xs:boolean">
+        <xsl:param name="importing" as="element()"/><!-- o:import in selection phase, o:insert-controls in merge phase -->
+        <xsl:param name="candidate" as="element(o:control)"/>
+        <xsl:variable name="include-reasons" as="xs:boolean+">
+            <!-- we are not optimizing for performance here; nothing is done to prevent all checks even if the first passes -->
+            <!--<xsl:sequence select="empty($importing/include)"/>-->
+            <xsl:sequence select="exists($importing/include-all)"/>
+            <xsl:sequence select="some $c in ($importing/include-controls/with-id)
+                satisfies ($c = $candidate/@id)"/>
+            <xsl:sequence select="some $c in ($importing/include-controls[o:calls-parents(.)]/with-id)
+                satisfies ($c = $candidate/descendant::control/@id)"/>
+            <xsl:sequence select="some $c in ($importing/include-controls[o:calls-children(.)]/with-id)
+                satisfies ($c = $candidate/ancestor::control/@id)"/>
+            <xsl:sequence select="some $m in ($importing/include-controls/matching[@pattern != ''])
+                satisfies (matches($candidate/@id,$m/@pattern/o:glob-as-regex(string(.)) ))"/>
+            <xsl:sequence select="some $m in ($importing/include-controls[o:calls-parents(.)]/matching[@pattern != '']), $a in $candidate/descendant::control 
+                satisfies (matches($a/@id,$m/@pattern/o:glob-as-regex(string(.))))"/>
+            <xsl:sequence select="some $m in ($importing/include-controls[o:calls-children(.)]/matching[@pattern != '']), $a in $candidate/ancestor::control 
+                satisfies (matches($a/@id,$m/@pattern/o:glob-as-regex(string(.))))"/>
+        </xsl:variable>
+        <xsl:variable name="exclude-reasons" as="xs:boolean+">
+            <xsl:sequence select="exists($candidate/parent::control) and $importing/include-all/@with-child-controls='no'"/>
+            <xsl:sequence select="some $c in ($importing/exclude-controls/with-id) satisfies ($c = $candidate/@id)"/>
+            <xsl:sequence select="some $c in ($importing/exclude-controls[o:calls-parents(.)]/with-id)
+                satisfies ($c = $candidate/descendant::control/@id)"/>
+            <xsl:sequence select="some $c in ($importing/exclude-controls[o:calls-children(.)]/with-id)
+                satisfies ($c = $candidate/ancestor::control/@id)"/>
+            <xsl:sequence select="some $m in ($importing/exclude-controls/matching[@pattern != ''])
+                satisfies (matches($candidate/@id,$m/@pattern/o:glob-as-regex(string(.))))"/>
+            <xsl:sequence select="some $m in ($importing/exclude-controls[o:calls-parents(.)]/matching[@pattern != '']), $a in $candidate/descendant::control
+                satisfies (matches($a/@id,$m/@pattern/o:glob-as-regex(string(.))))"/>
+            <xsl:sequence select="some $m in ($importing/exclude-controls[o:calls-children(.)]/matching[@pattern != '']), $a in $candidate/ancestor::control
+                satisfies (matches($a/@id,$m/@pattern/o:glob-as-regex(string(.))))"/>
+        </xsl:variable>
+        <!-- predicate [.] filters reasons as booleans -->
+        <xsl:sequence select="exists($include-reasons[.]) and empty($exclude-reasons[.])"/>
+    </xsl:function>
+    
+    <xsl:function name="o:calls-children" as="xs:boolean">
+        <xsl:param name="caller" as="element()"/>
+        <xsl:sequence select="$caller/@with-child-controls='yes'"/>
+    </xsl:function>
+    
+    <xsl:function name="o:calls-parents" as="xs:boolean">
+        <xsl:param name="caller" as="element()"/>
+        <xsl:sequence select="not($caller/@with-parent-controls='no')"/>
+    </xsl:function>
+
+    <xsl:function name="opr:catalog-identifier" as="xs:string">
+        <xsl:param name="catalog" as="element(o:catalog)"/>
+        <xsl:sequence select="$catalog/(@uuid,document-uri(root(.)))[1]"/>
+    </xsl:function>
+
+</xsl:stylesheet>
diff --git a/src/utils/util/resolver-pipeline/testing/1_selected/select.xspec b/src/utils/util/resolver-pipeline/testing/1_selected/select.xspec
index b14ce0adef..7f94a578ef 100644
--- a/src/utils/util/resolver-pipeline/testing/1_selected/select.xspec
+++ b/src/utils/util/resolver-pipeline/testing/1_selected/select.xspec
@@ -156,29 +156,36 @@
                 test="$x:result/o:selection/@uuid = $ov:catalog_uuid"/>
         </x:scenario>
         <x:scenario label="Profile select include call control-id">
-            <x:context>
+            <x:variable name="ov:profile-using-with-id" as="element(o:profile)">
                 <profile>
                     <import href="{$ov:filedir}/catalogs/xyz-tiny_catalog.xml">
                         <include-controls>
+                            <with-id>x2</with-id>
                             <with-id>x1</with-id>
                         </include-controls>
                     </import>
                 </profile>
-            </x:context>
-    
-            <x:expect label="Control x1, in its group, with other groups empty">
+            </x:variable>
+            <x:context select="$ov:profile-using-with-id"/>
+            <x:expect label="Control x1 and x2, in their group, with other groups empty">
                 <profile>
                     <selection uuid="..." opr:src="...">
                         <metadata>...</metadata>
                         <group opr:id="...">
                             <title>Group X of XYZ</title>
                             <control id="x1" opr:id="..."><title>Control X1</title></control>
+                            <control id="x2" opr:id="..."><title>Control X2</title></control>
                         </group>
                        <group opr:id="..."><title>Group Y of XYZ</title></group>
                        <group opr:id="..."><title>Group Z of XYZ</title></group>
                    </selection>
                 </profile>
             </x:expect>
+            <!-- Assertions about the order of controls in output catalog are relevant for merge phase. -->
+            <x:expect label="Order of controls in output is x1, x2 as in the input catalog."
+                test="$x:result//o:control/@id/string()" select="('x1','x2')"/>
+            <x:expect label="In this case, order of controls in output does not match order of with-id elements in profile."
+                test="not(deep-equal($x:result//o:control/@id/string(), $ov:profile-using-with-id//o:control/@id/string()))"/>
         </x:scenario>
     
         <x:scenario label="Profile select include call match">
@@ -286,6 +293,70 @@
             </x:expect>
         </x:scenario>
     
+        <x:scenario label="Default value of 'with-parent-controls' (yes)">
+            <x:context>
+                <profile>
+                    <import href="{$ov:filedir}/catalogs/xyz-tiny_catalog.xml">
+                        <include-controls with-parent-controls="yes">
+                            <with-id>z3.a-1</with-id>
+                        </include-controls>
+                    </import>
+                </profile>
+            </x:context>
+            
+            <x:expect label="Control Z3-A-1 and all its ancestors">
+                <profile>
+                    <selection uuid="..." opr:src="...">
+                        <metadata>...</metadata>
+                        <group opr:id="...">
+                            <title>Group X of XYZ</title>
+                        </group>
+                        <group opr:id="...">
+                            <title>Group Y of XYZ</title>
+                        </group>
+                        <group opr:id="...">
+                            <title>Group Z of XYZ</title>
+                            <control id="z3" opr:id="..."><title>Control Z3</title>
+                                <control id="z3.a" opr:id="..."><title>Control Z3-A</title>
+                                    <control id="z3.a-1" opr:id="..."><title>Control Z3-A-1</title></control>
+                                </control>
+                            </control>
+                        </group>
+                    </selection>
+                </profile>
+            </x:expect>
+        </x:scenario>
+
+        <x:scenario label="Nondefault value of 'with-parent-controls' (no)">
+            <x:context>
+                <profile>
+                    <import href="{$ov:filedir}/catalogs/xyz-tiny_catalog.xml">
+                        <include-controls with-parent-controls="no">
+                            <with-id>z3.a-1</with-id>
+                        </include-controls>
+                    </import>
+                </profile>
+            </x:context>
+            
+            <x:expect label="Control Z3-A-1 without its ancestor controls">
+                <profile>
+                    <selection uuid="..." opr:src="...">
+                        <metadata>...</metadata>
+                        <group opr:id="...">
+                            <title>Group X of XYZ</title>
+                        </group>
+                        <group opr:id="...">
+                            <title>Group Y of XYZ</title>
+                        </group>
+                        <group opr:id="...">
+                            <title>Group Z of XYZ</title>
+                            <control id="z3.a-1" opr:id="..."><title>Control Z3-A-1</title></control>
+                        </group>
+                    </selection>
+                </profile>
+            </x:expect>
+        </x:scenario>
+
         <x:scenario label="Doubled import, exclusive call">
             <x:context>
                 <profile>
diff --git a/src/utils/util/resolver-pipeline/testing/3_merged/merge-as-is.xspec b/src/utils/util/resolver-pipeline/testing/3_merged/merge-as-is.xspec
index f262452115..f08929c155 100644
--- a/src/utils/util/resolver-pipeline/testing/3_merged/merge-as-is.xspec
+++ b/src/utils/util/resolver-pipeline/testing/3_merged/merge-as-is.xspec
@@ -1,52 +1,46 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <x:description xmlns="http://csrc.nist.gov/ns/oscal/1.0"
+    xmlns:o="http://csrc.nist.gov/ns/oscal/1.0"
     xmlns:x="http://www.jenitennison.com/xslt/xspec"
     xmlns:opr="http://csrc.nist.gov/ns/oscal/profile-resolution"
-    stylesheet="../../oscal-profile-resolve-merge.xsl">
-    <x:scenario label="Base">
-        <x:context>
-            <catalog uuid="zzz"/>
-        </x:context>
+    stylesheet="../../oscal-profile-resolve-merge.xsl"
+    xslt-version="3.0">
 
-        <x:expect label="root becomes root">
-            <catalog uuid="zzz"/>
-        </x:expect>
-    </x:scenario>
-    <x:scenario label="Single import, as-is merge">
-        <x:context>
-            <catalog>
-                <selection uuid="xyz-tiny_catalog" opr:id="...">
-                    <group id="x" opr:id="xyz-tiny_catalog#x">
-                        <title>Group X of XYZ</title>
-                        <control id="x1" opr:id="xyz-tiny_catalog#x1"><title>Control X1</title></control>
-                        <control id="x2" opr:id="xyz-tiny_catalog#x2"><title>Control X2</title></control>
-                        <control id="x3" opr:id="xyz-tiny_catalog#x3"><title>Control X3</title></control>
-                    </group>
-                    <group id="y" opr:id="xyz-tiny_catalog#y">
-                        <title>Group Y of XYZ</title>
-                        <control id="y1" opr:id="xyz-tiny_catalog#y1"><title>Control Y1</title></control>
-                        <control id="y2" opr:id="xyz-tiny_catalog#y2"><title>Control Y2</title></control>
-                        <control id="y3" opr:id="xyz-tiny_catalog#y3"><title>Control Y3</title></control>
-                    </group>
-                    <group id="z" opr:id="xyz-tiny_catalog#z">
-                        <title>Group Z of XYZ</title>
-                        <control id="z1" opr:id="xyz-tiny_catalog#z1"><title>Control Z1</title></control>
-                        <control id="z2" opr:id="xyz-tiny_catalog#z2"><title>Control Z2</title></control>
-                        <control id="z3" opr:id="xyz-tiny_catalog#z3"><title>Control Z3</title>
-                            <control id="z3.a" opr:id="xyz-tiny_catalog#z3.a"><title>Control Z3-A</title>
-                                <control id="z3.a-1" opr:id="xyz-tiny_catalog#z3.a-1"><title>Control Z3-A-1</title></control>
+    <x:scenario label="Tests for match=catalog[merge/as-is=$true-content] priority=12 template">
+        <x:scenario label="Single import, as-is merge">
+            <x:context>
+                <catalog>
+                    <selection uuid="xyz-tiny_catalog" opr:id="...">
+                        <group id="x" opr:id="xyz-tiny_catalog#x">
+                            <title>Group X of XYZ</title>
+                            <control id="x1" opr:id="xyz-tiny_catalog#x1"><title>Control X1</title></control>
+                            <control id="x2" opr:id="xyz-tiny_catalog#x2"><title>Control X2</title></control>
+                            <control id="x3" opr:id="xyz-tiny_catalog#x3"><title>Control X3</title></control>
+                        </group>
+                        <group id="y" opr:id="xyz-tiny_catalog#y">
+                            <title>Group Y of XYZ</title>
+                            <control id="y1" opr:id="xyz-tiny_catalog#y1"><title>Control Y1</title></control>
+                            <control id="y2" opr:id="xyz-tiny_catalog#y2"><title>Control Y2</title></control>
+                            <control id="y3" opr:id="xyz-tiny_catalog#y3"><title>Control Y3</title></control>
+                        </group>
+                        <group id="z" opr:id="xyz-tiny_catalog#z">
+                            <title>Group Z of XYZ</title>
+                            <control id="z1" opr:id="xyz-tiny_catalog#z1"><title>Control Z1</title></control>
+                            <control id="z2" opr:id="xyz-tiny_catalog#z2"><title>Control Z2</title></control>
+                            <control id="z3" opr:id="xyz-tiny_catalog#z3"><title>Control Z3</title>
+                                <control id="z3.a" opr:id="xyz-tiny_catalog#z3.a"><title>Control Z3-A</title>
+                                    <control id="z3.a-1" opr:id="xyz-tiny_catalog#z3.a-1"><title>Control Z3-A-1</title></control>
+                                </control>
                             </control>
-                        </control>
-                    </group>
-                </selection>
-                <merge>
-                    <as-is>true</as-is>
-                </merge>
-            </catalog>
-        </x:context>
-        <x:expect label="XYZ catalog with original grouping">
-            <catalog>
-
+                        </group>
+                    </selection>
+                    <merge>
+                        <as-is>true</as-is>
+                    </merge>
+                </catalog>
+            </x:context>
+            <x:expect label="XYZ catalog with original grouping">
+                <catalog>
                     <group id="x">
                         <title>Group X of XYZ</title>
                         <control id="x1"><title>Control X1</title></control>
@@ -69,182 +63,568 @@
                             </control>
                         </control>
                     </group>
-            </catalog>
-        </x:expect>
-    </x:scenario>
-    <x:scenario label="Parallel imports, as-is merge">
-        <x:context>
-            <catalog>
-                <selection id="xyz-tiny_catalog" opr:id="xyz-tiny_catalog#xyz-tiny_catalog">
-                    <group id="x" opr:id="xyz-tiny_catalog#x">
+                </catalog>
+            </x:expect>
+        </x:scenario>
+        <x:scenario label="Parallel imports, as-is merge">
+            <x:context>
+                <catalog>
+                    <selection id="xyz-tiny_catalog" opr:id="xyz-tiny_catalog#xyz-tiny_catalog">
+                        <group id="x" opr:id="xyz-tiny_catalog#x">
+                            <title>Group X of XYZ</title>
+                            <control id="x1" opr:id="xyz-tiny_catalog#x1"><title>Control X1</title></control>
+                        </group>
+                        <group id="z" opr:id="xyz-tiny_catalog#z">
+                            <title>Group Z of XYZ</title>
+                            <control id="z1" opr:id="xyz-tiny_catalog#z1"><title>Control Z1</title></control>
+                            <control id="z3" opr:id="xyz-tiny_catalog#z3"><title>Control Z3</title>
+                                <control id="z3.a" opr:id="xyz-tiny_catalog#z3.a"><title>Control Z3-A</title>
+                                    <control id="z3.a-1" opr:id="xyz-tiny_catalog#z3.a-1"><title>Control Z3-A-1</title></control>
+                                </control>
+                            </control>
+                        </group>
+                    </selection>
+                    <selection id="xyz-tiny_catalog" opr:id="xyz-tiny_catalog#xyz-tiny_catalog">
+                        <group id="x" opr:id="xyz-tiny_catalog#x">
+                            <title>Group X of XYZ</title>
+                            <control id="x1" opr:id="xyz-tiny_catalog#x1"><title>Control X1</title></control>
+                            <control id="x2" opr:id="xyz-tiny_catalog#x2"><title>Control X2</title></control>
+                        </group>
+                        <group id="y" opr:id="xyz-tiny_catalog#y">
+                            <title>Group Y of XYZ</title>
+                            <control id="y1" opr:id="xyz-tiny_catalog#y1"><title>Control Y1</title></control>
+                            <control id="y2" opr:id="xyz-tiny_catalog#y2"><title>Control Y2</title></control>
+                            <control id="y3" opr:id="xyz-tiny_catalog#y3"><title>Control Y3</title></control>
+                        </group>
+                        <group id="z" opr:id="xyz-tiny_catalog#z">
+                            <title>Group Z of XYZ</title>
+                            <control id="z3" opr:id="xyz-tiny_catalog#z3"><title>Control Z3</title>
+                                <control id="z3.a" opr:id="xyz-tiny_catalog#z3.a"><title>Control Z3-A</title>
+                                    <control id="z3.a-1" opr:id="xyz-tiny_catalog#z3.a-1"><title>Control Z3-A-1</title></control>
+                                </control>
+                            </control>
+                        </group>
+                    </selection>
+                    <merge>
+                        <as-is>true</as-is>
+                    </merge>
+                </catalog>
+            </x:context>
+            <x:expect label="XYZ catalog merged, with some redundancy">
+                <catalog>
+                    <group id="x">
                         <title>Group X of XYZ</title>
-                        <control id="x1" opr:id="xyz-tiny_catalog#x1"><title>Control X1</title></control>
+                        <control id="x1"><title>Control X1</title></control>
+                        <control id="x1"><title>Control X1</title></control>
+                        <control id="x2"><title>Control X2</title></control>
                     </group>
-                    <group id="z" opr:id="xyz-tiny_catalog#z">
+                    <group id="z">
                         <title>Group Z of XYZ</title>
-                        <control id="z1" opr:id="xyz-tiny_catalog#z1"><title>Control Z1</title></control>
-                        <control id="z3" opr:id="xyz-tiny_catalog#z3"><title>Control Z3</title>
-                            <control id="z3.a" opr:id="xyz-tiny_catalog#z3.a"><title>Control Z3-A</title>
-                                <control id="z3.a-1" opr:id="xyz-tiny_catalog#z3.a-1"><title>Control Z3-A-1</title></control>
+                        <control id="z1"><title>Control Z1</title></control>
+                        <control id="z3"><title>Control Z3</title>
+                            <control id="z3.a"><title>Control Z3-A</title>
+                                <control id="z3.a-1"><title>Control Z3-A-1</title></control>
+                            </control>
+                        </control>
+                        <control id="z3"><title>Control Z3</title>
+                            <control id="z3.a"><title>Control Z3-A</title>
+                                <control id="z3.a-1"><title>Control Z3-A-1</title></control>
                             </control>
                         </control>
                     </group>
-                </selection>
-                <selection id="xyz-tiny_catalog" opr:id="xyz-tiny_catalog#xyz-tiny_catalog">
-                    <group id="x" opr:id="xyz-tiny_catalog#x">
-                        <title>Group X of XYZ</title>
-                        <control id="x1" opr:id="xyz-tiny_catalog#x1"><title>Control X1</title></control>
-                        <control id="x2" opr:id="xyz-tiny_catalog#x2"><title>Control X2</title></control>
-                    </group>
-                    <group id="y" opr:id="xyz-tiny_catalog#y">
+                    <group id="y">
                         <title>Group Y of XYZ</title>
-                        <control id="y1" opr:id="xyz-tiny_catalog#y1"><title>Control Y1</title></control>
-                        <control id="y2" opr:id="xyz-tiny_catalog#y2"><title>Control Y2</title></control>
-                        <control id="y3" opr:id="xyz-tiny_catalog#y3"><title>Control Y3</title></control>
+                        <control id="y1"><title>Control Y1</title></control>
+                        <control id="y2"><title>Control Y2</title></control>
+                        <control id="y3"><title>Control Y3</title></control>
                     </group>
-                    <group id="z" opr:id="xyz-tiny_catalog#z">
-                        <title>Group Z of XYZ</title>
-                        <control id="z3" opr:id="xyz-tiny_catalog#z3"><title>Control Z3</title>
-                            <control id="z3.a" opr:id="xyz-tiny_catalog#z3.a"><title>Control Z3-A</title>
-                                <control id="z3.a-1" opr:id="xyz-tiny_catalog#z3.a-1"><title>Control Z3-A-1</title></control>
-                            </control>
-                        </control>
+                </catalog>
+            </x:expect>
+        </x:scenario>
+        <x:scenario label="Merge with loose parameters">
+            <x:context>
+                <catalog>
+                    <selection id="xyz-tiny_catalog" opr:id="xyz-tiny_catalog#xyz-tiny_catalog">
+                        <group id="x" opr:id="xyz-tiny_catalog#x">
+                            <title>Group X of XYZ</title>
+                            <prop value="special" name="status"/>
+                            <param id="param-x">
+                                <label>Param X</label>
+                                <constraint>no control</constraint>
+                            </param>
+                            <control id="x1" opr:id="xyz-tiny_catalog#x1"><title>Control X1</title></control>
+                        </group>
+                    </selection>
+                    <selection id="xyz-tiny_catalog" opr:id="xyz-tiny_catalog#xyz-tiny_catalog">
+                        <group id="x" opr:id="xyz-tiny_catalog#x">
+                            <title>Group X of XYZ</title>
+                            <prop value="special" name="status"/>
+                            <param id="param-x">
+                                <select>
+                                    <choice>some choice</choice>
+                                    <choice>some other choice</choice>
+                                </select>
+                            </param>
+                            <control id="x1" opr:id="xyz-tiny_catalog#x1"><title>Control X1</title></control>
+                            <control id="x2" opr:id="xyz-tiny_catalog#x2"><title>Control X2</title></control>
+                        </group>
+                    </selection>
+                    <merge>
+                        <as-is>true</as-is>
+                    </merge>
+                </catalog>
+            </x:context>
+            <x:expect label="Output has loose parameters with redundancy">
+                <catalog>
+                    <group id="x">
+                        <title>Group X of XYZ</title>
+                        <prop value="special" name="status"/>
+                        <prop value="special" name="status"/>
+                        <param id="param-x">
+                            <label>Param X</label>
+                            <constraint>no control</constraint>
+                        </param>
+                        <param id="param-x">
+                            <select>
+                                <choice>some choice</choice>
+                                <choice>some other choice</choice>
+                            </select>
+                        </param>
+                        <control id="x1"><title>Control X1</title></control>
+                        <control id="x1"><title>Control X1</title></control>
+                        <control id="x2"><title>Control X2</title></control>
                     </group>
-                </selection>
-                <merge>
-                    <as-is>true</as-is>
-                </merge>
-            </catalog>
-        </x:context>
-        <x:expect label="XYZ catalog merged, with some redundancy">
-            <catalog>
-                <group id="x">
-                    <title>Group X of XYZ</title>
+                </catalog>
+            </x:expect>
+        </x:scenario>
+        <x:scenario label="Catalog with attribute, metadata, and modify child">
+            <x:context>
+                <catalog uuid="zzz">
+                    <metadata>
+                        <title>Test Profile</title>
+                        <last-modified>2019-11-13T12:41:07.061-05:00</last-modified>
+                        <version>1.3</version>
+                        <oscal-version>1.0.2</oscal-version>
+                        <prop name="resolution-tool" value="OSCAL Profile Resolver XSLT Pipeline OPRXP" />
+                        <link href="urn:UNKNOWN" rel="source-profile" />
+                    </metadata>
+                    <selection uuid="xyz-tiny_catalog">
+                        <control id="x1"><title>Control X1</title></control>
+                    </selection>
+                    <merge>
+                        <as-is>true</as-is>
+                    </merge>
+                    <modify>
+                        <set-parameter param-id="a1_prm1">
+                            <constraint>
+                                <description>
+                                    <p>at least every 3 years</p>
+                                </description>
+                            </constraint>
+                        </set-parameter>
+                    </modify>
+                </catalog>
+            </x:context>
+            <x:expect label="Output includes catalog attribute, metadata, and modify child">
+                <catalog uuid="zzz">
+                    <metadata>
+                        <title>Test Profile</title>
+                        <last-modified>2019-11-13T12:41:07.061-05:00</last-modified>
+                        <version>1.3</version>
+                        <oscal-version>1.0.2</oscal-version>
+                        <prop name="resolution-tool" value="OSCAL Profile Resolver XSLT Pipeline OPRXP" />
+                        <link href="urn:UNKNOWN" rel="source-profile" />
+                    </metadata>
                     <control id="x1"><title>Control X1</title></control>
+                    <modify>
+                        <set-parameter param-id="a1_prm1">
+                            <constraint>
+                                <description>
+                                    <p>at least every 3 years</p>
+                                </description>
+                            </constraint>
+                        </set-parameter>
+                    </modify>
+                </catalog>
+            </x:expect>
+        </x:scenario>
+        <x:scenario label="Catalog with back matter inside and outside selection">
+            <x:context>
+                <catalog uuid="zzz">
+                    <selection uuid="xyz-tiny_catalog">
+                        <control id="x1"><title>Control X1</title></control>
+                        <back-matter>
+                            <resource uuid="0050231f-4fd0-43d6-8fa0-431367cd83e2">
+                                <title>Ref BBB</title>
+                                <citation>
+                                    <text>Bbb bbbbb Bbb b.</text>
+                                </citation>
+                                <rlink href="bbb.html"/>
+                            </resource>
+                        </back-matter>
+                    </selection>
+                    <merge>
+                        <as-is>true</as-is>
+                    </merge>
+                    <back-matter>
+                        <resource uuid="0050231f-4fd0-43d6-8fa0-431367cd83e1">
+                            <title>Ref AAA</title>
+                            <citation>
+                                <text>Aaaa aaaa aaaa</text>
+                            </citation>
+                            <rlink href="aaa.html"/>
+                        </resource>
+                    </back-matter>
+                </catalog>
+            </x:context>
+            <x:expect label="Output includes consolidated back matter">
+                <catalog uuid="zzz">
                     <control id="x1"><title>Control X1</title></control>
-                    <control id="x2"><title>Control X2</title></control>
-                </group>
-                <group id="z">
-                    <title>Group Z of XYZ</title>
-                    <control id="z1"><title>Control Z1</title></control>
-                    <control id="z3"><title>Control Z3</title>
-                        <control id="z3.a"><title>Control Z3-A</title>
-                            <control id="z3.a-1"><title>Control Z3-A-1</title></control>
-                        </control>
-                    </control>
-                    <control id="z3"><title>Control Z3</title>
-                        <control id="z3.a"><title>Control Z3-A</title>
-                            <control id="z3.a-1"><title>Control Z3-A-1</title></control>
-                        </control>
-                    </control>
-                </group>
-                <group id="y">
-                    <title>Group Y of XYZ</title>
-                    <control id="y1"><title>Control Y1</title></control>
-                    <control id="y2"><title>Control Y2</title></control>
-                    <control id="y3"><title>Control Y3</title></control>
-                </group>
-            </catalog>
-        </x:expect>
+                    <back-matter>
+                        <resource uuid="0050231f-4fd0-43d6-8fa0-431367cd83e2">
+                            <title>Ref BBB</title>
+                            <citation>
+                                <text>Bbb bbbbb Bbb b.</text>
+                            </citation>
+                            <rlink href="bbb.html"/>
+                        </resource>
+                        <resource uuid="0050231f-4fd0-43d6-8fa0-431367cd83e1">
+                            <title>Ref AAA</title>
+                            <citation>
+                                <text>Aaaa aaaa aaaa</text>
+                            </citation>
+                            <rlink href="aaa.html"/>
+                        </resource>
+                    </back-matter>
+                </catalog>
+            </x:expect>
+        </x:scenario>
     </x:scenario>
-    <x:scenario label="Ugly merge with loose parameters and stuff">
-        <x:context>
-            <catalog>
-                <selection id="xyz-tiny_catalog" opr:id="xyz-tiny_catalog#xyz-tiny_catalog">
-                    <group id="x" opr:id="xyz-tiny_catalog#x">
+
+    <x:scenario label="Tests for o:merge-groups-as-is template">
+        <x:scenario label="$merging is sequence of selection elements ">
+            <x:scenario label="with duplicate identifiers">
+                <x:call template="o:merge-groups-as-is">
+                    <x:param name="merging" as="element(o:selection)+">
+                        <selection uuid="a"><title>uuid a</title></selection>
+                        <selection uuid="a"><title>uuid a again</title></selection>
+                        <selection opr:id="b"><title>opr:id b</title></selection>
+                        <selection opr:id="b"><title>opr:id b again</title></selection>
+                        <selection uuid="c"><title>uuid c</title></selection>
+                        <selection opr:id="c"><title>opr:id c</title></selection>
+                    </x:param>
+                </x:call>
+                <x:expect label="One output per unique identifier name/value pair, but opr:id is omitted">
+                    <selection uuid="a"><title>uuid a</title></selection>
+                    <selection><title>opr:id b</title></selection>
+                    <selection uuid="c"><title>uuid c</title></selection>
+                </x:expect>
+            </x:scenario>
+            <x:scenario label="ungrouped with children other than title, param, control">
+                <x:call template="o:merge-groups-as-is">
+                    <x:param name="merging" as="element(o:selection)+" select="//o:selection">
+                        <catalog>
+                          <selection id="xyz-tiny_catalog" opr:id="xyz-tiny_catalog#xyz-tiny_catalog">
+                              <prop value="special" name="status"/>
+                              <param id="param-x">
+                                  <label>Param X</label>
+                                  <constraint>no control</constraint>
+                              </param>
+                              <control id="x1" opr:id="xyz-tiny_catalog#x1"><title>Control X1</title></control>
+                              <back-matter>
+                                  <resource opr:id="ref001">
+                                      <title>Ref AAA</title>
+                                  </resource>
+                              </back-matter>
+                          </selection>
+                          <merge>
+                              <as-is>true</as-is>
+                          </merge>
+                      </catalog>
+                    </x:param>
+                </x:call>
+                <!-- This template's output has back-matter in the "wrong" place,
+                    but that is OK because the caller ignores back-matter. -->
+                <x:expect label="'other' children followed by params and controls">
+                    <selection id="xyz-tiny_catalog">
+                        <prop value="special" name="status"/>
+                        <back-matter>
+                            <resource>
+                                <title>Ref AAA</title>
+                            </resource>
+                        </back-matter>
+                        <param id="param-x">
+                            <label>Param X</label>
+                            <constraint>no control</constraint>
+                        </param>
+                        <control id="x1"><title>Control X1</title></control>
+                    </selection>
+                </x:expect>
+            </x:scenario>
+            <x:scenario label="grouped with children other than title, param, control">
+                <x:call template="o:merge-groups-as-is">
+                    <x:param name="merging" as="element(o:selection)+" select="//o:selection">
+                        <catalog>
+                            <selection id="xyz-tiny_catalog" opr:id="xyz-tiny_catalog#xyz-tiny_catalog">
+                                <group>
+                                    <title>Group X of XYZ</title>
+                                    <control id="x1" opr:id="xyz-tiny_catalog#x1"><title>Control X1</title></control>
+                                </group>
+                                <back-matter>
+                                    <resource opr:id="ref001">
+                                        <title>Ref AAA</title>
+                                    </resource>
+                                </back-matter>
+                            </selection>
+                            <merge>
+                                <as-is>true</as-is>
+                            </merge>
+                        </catalog>
+                    </x:param>
+                </x:call>
+                <!-- This template's output has back-matter in the "wrong" place,
+                    but that is OK because the caller ignores back-matter. -->
+                <x:expect label="'other' children followed by group">
+                    <selection id="xyz-tiny_catalog">
+                        <back-matter>
+                            <resource>
+                                <title>Ref AAA</title>
+                            </resource>
+                        </back-matter>
+                        <group>
+                            <title>Group X of XYZ</title>
+                            <control id="x1"><title>Control X1</title></control>
+                        </group>
+                    </selection>
+                </x:expect>
+            </x:scenario>
+            <x:scenario label="grouped but no controls in groups">
+                <x:call template="o:merge-groups-as-is">
+                    <x:param name="merging" as="element(o:selection)+" select="//o:selection">
+                        <catalog>
+                            <selection id="xyz-tiny_catalog" opr:id="xyz-tiny_catalog#xyz-tiny_catalog">
+                                <group>
+                                    <title>Group X of XYZ</title>
+                                </group>
+                            </selection>
+                            <merge>
+                                <as-is>true</as-is>
+                            </merge>
+                        </catalog>
+                    </x:param>
+                </x:call>
+                <x:expect label="selection but no groups">
+                    <selection id="xyz-tiny_catalog"/>
+                </x:expect>
+            </x:scenario>
+            <x:scenario label="grouped with controls not as children but only deeper descendants">
+                <x:call template="o:merge-groups-as-is">
+                    <x:param name="merging" as="element(o:selection)+" select="//o:selection">
+                        <catalog>
+                            <selection id="xyz-tiny_catalog" opr:id="xyz-tiny_catalog#xyz-tiny_catalog">
+                                <group>
+                                    <title>Group X of XYZ</title>
+                                    <group>
+                                        <title>Group XX</title>
+                                        <control id="x1" opr:id="xyz-tiny_catalog#x1"><title>Control X1</title></control>
+                                    </group>
+                                </group>
+                            </selection>
+                            <merge>
+                                <as-is>true</as-is>
+                            </merge>
+                        </catalog>
+                    </x:param>
+                </x:call>
+                <x:expect label="Groups are retained in output">
+                    <selection id="xyz-tiny_catalog">
+                        <group>
+                            <title>Group X of XYZ</title>
+                            <group>
+                                <title>Group XX</title>
+                                <control id="x1"><title>Control X1</title></control>
+                            </group>
+                        </group>
+                    </selection>
+                </x:expect> 
+            </x:scenario>
+            <x:scenario label="with params and controls that need merging">
+                <x:call template="o:merge-groups-as-is">
+                    <x:param name="merging" as="element(o:selection)+" select="//o:selection">
+                        <catalog>
+                            <selection id="xyz-tiny_catalog" opr:id="xyz-tiny_catalog#xyz-tiny_catalog">
+                                <param id="param-x">
+                                    <label>Param X</label>
+                                    <constraint>no control</constraint>
+                                </param>
+                                <control id="x1" opr:id="xyz-tiny_catalog#x1"><title>Control X1</title></control>
+                            </selection>
+                            <selection id="xyz-tiny_catalog" opr:id="xyz-tiny_catalog#xyz-tiny_catalog">
+                                <param id="param-x">
+                                    <label>Param X</label>
+                                    <constraint>no control</constraint>
+                                </param>
+                                <control id="x1" opr:id="xyz-tiny_catalog#x1"><title>Control X1</title></control>
+                            </selection>
+                            <merge>
+                                <as-is>true</as-is>
+                                <combine method="use-first"/>
+                            </merge>
+                        </catalog>
+                    </x:param>
+                </x:call>
+                <x:expect label="merged params and controls, following use-first directive">
+                    <selection id="xyz-tiny_catalog">
+                        <param id="param-x">
+                            <label>Param X</label>
+                            <constraint>no control</constraint>
+                        </param>
+                        <control id="x1"><title>Control X1</title></control>
+                    </selection>
+                </x:expect>
+            </x:scenario>
+        </x:scenario>
+        <x:scenario label="$merging is sequence of group elements ">
+            <x:scenario label="with duplicate identifiers">
+                <x:call template="o:merge-groups-as-is">
+                    <x:param name="merging" as="element(o:group)+">
+                        <group id="a"><title>id a</title></group>
+                        <group id="a"><title>id a again</title></group>
+                        <group opr:id="b"><title>opr:id b</title></group>
+                        <group opr:id="b"><title>opr:id b again</title></group>
+                        <group id="c"><title>id c</title></group>
+                        <group opr:id="c"><title>opr:id c</title></group>
+                    </x:param>
+                </x:call>
+                <x:expect label="One output per unique identifier name/value pair, but opr:id is omitted">
+                    <group id="a"><title>id a</title></group>
+                    <group><title>opr:id b</title></group>
+                    <group id="c"><title>id c</title></group>
+                </x:expect>
+            </x:scenario>
+            <x:scenario label="with children other than title, param, control">
+                <x:call template="o:merge-groups-as-is">
+                    <x:param name="merging" as="element(o:group)+" select="//o:group">
+                        <catalog>
+                            <selection id="xyz-tiny_catalog" opr:id="xyz-tiny_catalog#xyz-tiny_catalog">
+                                <group>
+                                    <title>Group X of XYZ</title>
+                                    <prop value="special" name="status"/>
+                                    <param id="param-x">
+                                        <label>Param X</label>
+                                        <constraint>no control</constraint>
+                                    </param>
+                                    <control id="x1" opr:id="xyz-tiny_catalog#x1"><title>Control X1</title></control>
+                                </group>
+                                <group id="group-y">
+                                    <title>Group Y of XYZ</title>
+                                    <control id="y1" opr:id="xyz-tiny_catalog#y1"><title>Control Y1</title></control>
+                                </group>
+                            </selection>
+                            <merge>
+                                <as-is>true</as-is>
+                            </merge>
+                        </catalog>
+                    </x:param>
+                </x:call>
+                <x:expect label="groups with title followed by 'other' children, params, and controls">
+                    <group>
                         <title>Group X of XYZ</title>
                         <prop value="special" name="status"/>
                         <param id="param-x">
                             <label>Param X</label>
                             <constraint>no control</constraint>
                         </param>
-                        <control id="x1" opr:id="xyz-tiny_catalog#x1"><title>Control X1</title></control>
+                        <control id="x1"><title>Control X1</title></control>
                     </group>
-                    <group id="z" opr:id="xyz-tiny_catalog#z">
-                        <title>Group Z of XYZ</title>
-                        <control id="z1" opr:id="xyz-tiny_catalog#z1"><title>Control Z1</title></control>
-                        <control id="z3" opr:id="xyz-tiny_catalog#z3"><title>Control Z3</title>
-                            <control id="z3.a" opr:id="xyz-tiny_catalog#z3.a"><title>Control Z3-A</title>
-                                <control id="z3.a-1" opr:id="xyz-tiny_catalog#z3.a-1"><title>Control Z3-A-1</title></control>
-                            </control>
-                        </control>
+                    <group id="group-y">
+                        <title>Group Y of XYZ</title>
+                        <control id="y1"><title>Control Y1</title></control>
                     </group>
-                </selection>
-                <selection id="xyz-tiny_catalog" opr:id="xyz-tiny_catalog#xyz-tiny_catalog">
-                    <group id="x" opr:id="xyz-tiny_catalog#x">
+                </x:expect>
+            </x:scenario>
+            <x:scenario label="with nested groups">
+                <x:call template="o:merge-groups-as-is">
+                    <x:param name="merging" as="element(o:group)+" select="//o:selection/o:group">
+                        <catalog>
+                            <selection id="xyz-tiny_catalog" opr:id="xyz-tiny_catalog#xyz-tiny_catalog">
+                                <group>
+                                    <title>Group X of XYZ</title>
+                                    <prop value="special" name="status"/>
+                                    <param id="param-x">
+                                        <label>Param X</label>
+                                        <constraint>no control</constraint>
+                                    </param>
+                                    <control id="x1" opr:id="xyz-tiny_catalog#x1"><title>Control X1</title></control>
+                                </group>
+                                <group id="group-y">
+                                    <title>Group Y of XYZ</title>
+                                    <group id="group-yy">
+                                        <title>Group YY</title>
+                                        <control id="y1" opr:id="xyz-tiny_catalog#y1"><title>Control Y1</title></control>
+                                    </group>
+                                </group>
+                            </selection>
+                            <merge>
+                                <as-is>true</as-is>
+                            </merge>
+                        </catalog>
+                    </x:param>
+                </x:call>
+                <x:expect label="groups including nested group">
+                    <group>
                         <title>Group X of XYZ</title>
                         <prop value="special" name="status"/>
                         <param id="param-x">
-                            <select>
-                                <choice>some choice</choice>
-                                <choice>some other choice</choice>
-                            </select>
+                            <label>Param X</label>
+                            <constraint>no control</constraint>
                         </param>
-                        <control id="x1" opr:id="xyz-tiny_catalog#x1"><title>Control X1</title></control>
-                        <control id="x2" opr:id="xyz-tiny_catalog#x2"><title>Control X2</title></control>
+                        <control id="x1"><title>Control X1</title></control>
                     </group>
-                    <group id="y" opr:id="xyz-tiny_catalog#y">
+                    <group id="group-y">
                         <title>Group Y of XYZ</title>
-                        <control id="y1" opr:id="xyz-tiny_catalog#y1"><title>Control Y1</title></control>
-                        <control id="y2" opr:id="xyz-tiny_catalog#y2"><title>Control Y2</title></control>
-                        <control id="y3" opr:id="xyz-tiny_catalog#y3"><title>Control Y3</title></control>
+                        <group id="group-yy">
+                            <title>Group YY</title>
+                            <control id="y1"><title>Control Y1</title></control>
+                        </group>
                     </group>
-                    <group id="z" opr:id="xyz-tiny_catalog#z">
-                        <title>Group Z of XYZ</title>
-                        <control id="z3" opr:id="xyz-tiny_catalog#z3"><title>Control Z3</title>
-                            <control id="z3.a" opr:id="xyz-tiny_catalog#z3.a"><title>Control Z3-A</title>
-                                <control id="z3.a-1" opr:id="xyz-tiny_catalog#z3.a-1"><title>Control Z3-A-1</title></control>
-                            </control>
-                        </control>
+                </x:expect>
+            </x:scenario>
+            <x:scenario label="with controls not as children but only deeper descendants">
+                <x:call template="o:merge-groups-as-is">
+                    <x:param name="merging" as="element(o:group)+" select="//o:selection/o:group">
+                        <catalog>
+                            <selection id="xyz-tiny_catalog" opr:id="xyz-tiny_catalog#xyz-tiny_catalog">
+                                <group>
+                                    <title>Group X of XYZ</title>
+                                    <group>
+                                        <title>Group XX</title>
+                                        <control id="x1" opr:id="xyz-tiny_catalog#x1"><title>Control X1</title></control>
+                                    </group>
+                                </group>
+                            </selection>
+                            <merge>
+                                <as-is>true</as-is>
+                            </merge>
+                        </catalog>
+                    </x:param>
+                </x:call>
+                <x:expect label="Groups are retained in output">
+                    <group>
+                        <title>Group X of XYZ</title>
+                        <group>
+                            <title>Group XX</title>
+                            <control id="x1"><title>Control X1</title></control>
+                        </group>
                     </group>
-                </selection>
-                <merge>
-                    <as-is>true</as-is>
-                </merge>
-            </catalog>
-        </x:context>
-        <x:expect label="XYZ ugly merged, with extra redundancy">
-            <catalog>
-                <group id="x">
-                    <title>Group X of XYZ</title>
-                    <prop value="special" name="status"/>
-                    <prop value="special" name="status"/>
-                    <param id="param-x">
-                        <label>Param X</label>
-                        <constraint>no control</constraint>
-                    </param>
-                    <param id="param-x">
-                        <select>
-                            <choice>some choice</choice>
-                            <choice>some other choice</choice>
-                        </select>
-                    </param>
-                    <control id="x1"><title>Control X1</title></control>
-                    <control id="x1"><title>Control X1</title></control>
-                    <control id="x2"><title>Control X2</title></control>
-                </group>
-                <group id="z">
-                    <title>Group Z of XYZ</title>
-                    <control id="z1"><title>Control Z1</title></control>
-                    <control id="z3"><title>Control Z3</title>
-                        <control id="z3.a"><title>Control Z3-A</title>
-                            <control id="z3.a-1"><title>Control Z3-A-1</title></control>
-                        </control>
-                    </control>
-                    <control id="z3"><title>Control Z3</title>
-                        <control id="z3.a"><title>Control Z3-A</title>
-                            <control id="z3.a-1"><title>Control Z3-A-1</title></control>
-                        </control>
-                    </control>
-                </group>
-                <group id="y">
-                    <title>Group Y of XYZ</title>
-                    <control id="y1"><title>Control Y1</title></control>
-                    <control id="y2"><title>Control Y2</title></control>
-                    <control id="y3"><title>Control Y3</title></control>
-                </group>
-            </catalog>
-        </x:expect>
+                </x:expect> 
+            </x:scenario>
+        </x:scenario>
+        <x:scenario label="$merging is empty sequence">
+            <x:call template="o:merge-groups-as-is">
+                <x:param name="merging" select="()"/>
+            </x:call>
+            <x:expect label="Nothing" select="()"/>
+        </x:scenario>
     </x:scenario>
-
 </x:description>
diff --git a/src/utils/util/resolver-pipeline/testing/3_merged/merge-back-matter.xspec b/src/utils/util/resolver-pipeline/testing/3_merged/merge-back-matter.xspec
deleted file mode 100644
index 3c1e92ee7c..0000000000
--- a/src/utils/util/resolver-pipeline/testing/3_merged/merge-back-matter.xspec
+++ /dev/null
@@ -1,154 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?><x:description xmlns="http://csrc.nist.gov/ns/oscal/1.0"
-    xmlns:x="http://www.jenitennison.com/xslt/xspec" xmlns:opr="http://csrc.nist.gov/ns/oscal/profile-resolution" stylesheet="../../oscal-profile-resolve-merge.xsl">
-    <x:scenario label="Base">
-        <x:context>
-            <catalog/>
-        </x:context>
-
-        <x:expect label="profile becomes catalog">
-            <catalog/>
-        </x:expect>
-    </x:scenario>
-
-    <x:scenario label="Merge with back matter">
-        <x:context>
-            <catalog>
-                <selection uuid="xyz-tiny_catalog">
-                    <group id="x">
-                        <title>Group X of XYZ</title>
-                        <control id="x1" opr:id="xyz-tiny_catalog#x1"><title>Control X1</title></control>
-                    </group>
-                    <group id="z">
-                        <title>Group Z of XYZ</title>
-                        <control id="z1" opr:id="xyz-tiny_catalog#z1"><title>Control Z1</title></control>
-                        <control id="z3" opr:id="xyz-tiny_catalog#z3"><title>Control Z3</title>
-                            <control id="z3.a" opr:id="xyz-tiny_catalog#z3.a"><title>Control Z3-A</title>
-                                <control id="z3.a-1" opr:id="xyz-tiny_catalog#z3.a-1"><title>Control Z3-A-1</title></control>
-                            </control>
-                        </control>
-                    </group>
-                    <back-matter>
-                        <resource id="ref001">
-                            <title>Ref AAA</title>
-                            <citation>
-                                <text>Aaaa aaaa aaaa</text>
-                            </citation>
-                            <rlink href="aaa.html"/>
-                        </resource>
-                        <resource id="ref002">
-                            <title>Ref BBB</title>
-                            <citation>
-                                <text>Bbb bbbbb Bbb b.</text>
-                            </citation>
-                            <rlink href="bbb.html"/>
-                        </resource>
-                    </back-matter>
-                </selection>
-
-            </catalog>
-        </x:context>
-        <x:expect label="Losing structure but back matter comes through">
-            <catalog>
-                <control id="x1"><title>Control X1</title></control>
-                <control id="z1"><title>Control Z1</title></control>
-                <control id="z3"><title>Control Z3</title>
-                    <control id="z3.a"><title>Control Z3-A</title>
-                        <control id="z3.a-1">
-                            <title>Control Z3-A-1</title></control>
-                    </control>
-                </control>
-                <back-matter>
-                    <resource id="ref001">
-                        <title>Ref AAA</title>
-                        <citation>
-                            <text>Aaaa aaaa aaaa</text>
-                        </citation>
-                        <rlink href="aaa.html"/>
-                    </resource>
-                    <resource id="ref002">
-                        <title>Ref BBB</title>
-                        <citation>
-                            <text>Bbb bbbbb Bbb b.</text>
-                        </citation>
-                        <rlink href="bbb.html"/>
-                    </resource>
-                </back-matter>
-            </catalog>
-        </x:expect>
-    </x:scenario>
-
-    <x:scenario label="Merge as-is with back matter">
-        <x:context>
-            <catalog>
-                <selection uuid="xyz-tiny_catalog">
-                    <group id="x">
-                        <title>Group X of XYZ</title>
-                        <control id="x1" opr:id="xyz-tiny_catalog#x1"><title>Control X1</title></control>
-                    </group>
-                    <group id="z">
-                        <title>Group Z of XYZ</title>
-                        <control id="z1" opr:id="xyz-tiny_catalog#z1"><title>Control Z1</title></control>
-                        <control id="z3" opr:id="xyz-tiny_catalog#z3"><title>Control Z3</title>
-                            <control id="z3.a" opr:id="xyz-tiny_catalog#z3.a"><title>Control Z3-A</title>
-                                <control id="z3.a-1" opr:id="xyz-tiny_catalog#z3.a-1"><title>Control Z3-A-1</title></control>
-                            </control>
-                        </control>
-                    </group>
-                    <back-matter>
-                        <resource id="ref001">
-                            <title>Ref AAA</title>
-                            <citation>
-                                <text>Aaaa aaaa aaaa</text>
-                            </citation>
-                            <rlink href="aaa.html"/>
-                        </resource>
-                        <resource id="ref002">
-                            <title>Ref BBB</title>
-                            <citation>
-                                <text>Bbb bbbbb Bbb b.</text>
-                            </citation>
-                            <rlink href="bbb.html"/>
-                        </resource>
-                    </back-matter>
-                </selection>
-                <merge>
-                    <as-is>true</as-is>
-                </merge>
-            </catalog>
-        </x:context>
-        <x:expect label="Back matter comes through">
-            <catalog>
-                <group id="x">
-                    <title>Group X of XYZ</title>
-                    <control id="x1"><title>Control X1</title></control>
-                </group>
-                <group id="z">
-                    <title>Group Z of XYZ</title>
-                    <control id="z1"><title>Control Z1</title></control>
-                    <control id="z3"><title>Control Z3</title>
-                        <control id="z3.a"><title>Control Z3-A</title>
-                            <control id="z3.a-1">
-                                <title>Control Z3-A-1</title></control>
-                        </control>
-                    </control>
-                </group>
-                <back-matter>
-                    <resource id="ref001">
-                        <title>Ref AAA</title>
-                        <citation>
-                            <text>Aaaa aaaa aaaa</text>
-                        </citation>
-                        <rlink href="aaa.html"/>
-                    </resource>
-                    <resource id="ref002">
-                        <title>Ref BBB</title>
-                        <citation>
-                            <text>Bbb bbbbb Bbb b.</text>
-                        </citation>
-                        <rlink href="bbb.html"/>
-                    </resource>
-                </back-matter>
-            </catalog>
-        </x:expect>
-    </x:scenario>
-</x:description>
diff --git a/src/utils/util/resolver-pipeline/testing/3_merged/merge-combine.xspec b/src/utils/util/resolver-pipeline/testing/3_merged/merge-combine.xspec
new file mode 100644
index 0000000000..6a514161b1
--- /dev/null
+++ b/src/utils/util/resolver-pipeline/testing/3_merged/merge-combine.xspec
@@ -0,0 +1,275 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<x:description xmlns="http://csrc.nist.gov/ns/oscal/1.0"
+    xmlns:o="http://csrc.nist.gov/ns/oscal/1.0"
+    xmlns:opr="http://csrc.nist.gov/ns/oscal/profile-resolution"
+    xmlns:ov="http://csrc.nist.gov/ns/oscal/xspec/variable"
+    xmlns:x="http://www.jenitennison.com/xslt/xspec"
+    stylesheet="../../oscal-profile-resolve-merge.xsl">
+
+    <!-- Override value of $in_xspec global XSLT variable so that error behavior
+        in "Error case: Elements of different kinds" scenario can differ for
+        testing vs. production usage. -->
+    <x:param name="in_xspec" select="true()"/>
+
+    <!-- These variables provide contexts that indicate how to combine elements. -->
+    <x:variable name="ov:combine-merge">
+        <catalog>
+            <merge>
+                <combine method="merge"/>
+            </merge>
+        </catalog>
+    </x:variable>
+    <x:variable name="ov:combine-use-first">
+        <catalog>
+            <merge>
+                <combine method="use-first"/>
+            </merge>
+        </catalog>
+    </x:variable>
+    <x:variable name="ov:combine-keep">
+        <catalog/>
+    </x:variable>
+
+    <x:scenario label="Tests for combine-elements template">
+        <x:variable name="ov:who" as="element(o:control)+" select="//o:control">
+            <selection>
+                <control id="a" attr="val"><title>Control A</title></control>
+                <control id="b"><title>Control B</title></control>
+                <control id="a" attr1="val1"><title>Control A1</title></control>
+            </selection>
+        </x:variable>
+        <x:scenario label="Typical case: $who is nonempty and context has ancestor catalog ">
+            <x:scenario label="with 'merge' method">
+                <x:context select="$ov:combine-merge"/>
+                <x:call template="combine-elements">
+                    <x:param name="who" select="$ov:who"/>
+                </x:call>
+                <x:expect label="Dispatches to handler for 'merge' method">
+                    <control id="a" attr="val" attr1="val1">
+                        <title>Control A</title>
+                        <title>Control A1</title>
+                    </control>
+                    <control id="b"><title>Control B</title></control>
+                </x:expect>
+            </x:scenario>
+            <x:scenario label="with 'use-first' method">
+                <x:context select="$ov:combine-use-first"/>
+                <x:call template="combine-elements">
+                    <x:param name="who" select="$ov:who"/>
+                </x:call>
+                <x:expect label="Dispatches to handler for 'use-first' method">
+                    <control id="a" attr="val"><title>Control A</title></control>
+                </x:expect>
+            </x:scenario>
+            <x:scenario label="with no method">
+                <x:context select="$ov:combine-keep"/>
+                <x:call template="combine-elements">
+                    <x:param name="who" select="$ov:who"/>
+                </x:call>
+                <x:expect label="Dispatches to handler for 'keep' method">
+                    <control id="a" attr="val"><title>Control A</title></control>
+                    <control id="b"><title>Control B</title></control>
+                    <control id="a" attr1="val1"><title>Control A1</title></control>
+                </x:expect>
+            </x:scenario>
+        </x:scenario>
+        <x:scenario label="Edge case: No elements">
+            <x:context select="$ov:combine-keep"/>
+            <x:call template="combine-elements">
+                <x:param name="who" as="empty-sequence()"/>
+            </x:call>
+            <x:expect label="Nothing"/>
+        </x:scenario>
+        <x:scenario label="Edge case that shouldn't happen: No catalog ancestor">
+            <x:context>
+                <not-catalog/>
+            </x:context>
+            <x:call template="combine-elements">
+                <x:param name="who" select="$ov:who"/>
+            </x:call>
+            <x:expect label="Nothing"/>
+        </x:scenario>
+    </x:scenario>
+
+    <x:scenario label="Tests for match=catalog[merge/combine/@method='merge'] priority=10 mode=o:combine-elements template">
+        <x:scenario label="Elements of same kind with duplicate id but distinct opr:id">
+            <x:context mode="o:combine-elements" select="$ov:combine-merge">
+                <x:param name="elements" as="element()+">
+                    <control id="a" opr:id="a"><title>Control A</title></control>
+                    <control id="a" opr:id="a1"><title>Control A1</title></control>
+                </x:param>
+            </x:context>
+            <x:expect label="Distinct elements">
+                <control id="a"><title>Control A</title></control>
+                <control id="a"><title>Control A1</title></control>
+            </x:expect>
+        </x:scenario>
+        <x:scenario label="Elements of same kind with duplicate identifier">
+            <x:context mode="o:combine-elements" select="$ov:combine-merge">
+                <x:param name="elements" as="element()+" select="//o:control">
+                    <catalog>
+                        <control id="a" attr="val"><title>Control A</title></control>
+                        <control id="b"><title>Control B</title></control>
+                        <control id="a" attr1="val1"><title>Control A1</title></control>
+                    </catalog>
+                </x:param>
+            </x:context>
+            <x:expect label="For each distinct identifier, one wrapper element and merged attributes and child elements">
+                <control id="a" attr="val" attr1="val1">
+                    <title>Control A</title>
+                    <title>Control A1</title>
+                </control>
+                <control id="b">
+                    <title>Control B</title>
+                </control>
+            </x:expect>
+        </x:scenario>
+        <x:scenario label="Edge case: Elements of same kind despite different notation">
+            <x:context mode="o:combine-elements" select="$ov:combine-merge">
+                <x:param name="elements" as="element()+" xmlns="foo" select="//*:control">
+                    <some-wrapper>
+                        <o:control id="a" attr="val"><o:title>Control A</o:title></o:control>
+                        <ccc:control xmlns:ccc="http://csrc.nist.gov/ns/oscal/1.0" id="b"><ccc:title>Control B</ccc:title></ccc:control>
+                        <control xmlns="http://csrc.nist.gov/ns/oscal/1.0" id="a" attr1="val1"><title>Control A1</title></control>
+                    </some-wrapper>
+                </x:param>
+            </x:context>
+            <x:expect label="Same result as in case of consistent notation, and no error">
+                <control id="a" attr="val" attr1="val1">
+                    <title>Control A</title>
+                    <title>Control A1</title>
+                </control>
+                <control id="b">
+                    <title>Control B</title>
+                </control>
+            </x:expect>
+        </x:scenario>
+        <x:scenario label="Error case: Elements of different kinds" catch="yes">
+            <x:context mode="o:combine-elements" select="$ov:combine-merge">
+                <x:param name="elements" as="element()+" select="//*:control">
+                    <selection>
+                        <control/>
+                        <control xmlns="foo"/>
+                    </selection>
+                </x:param>
+            </x:context>
+            <x:expect label="XSLT error, fatal when $in_xspec is true"
+                test="$x:result instance of map(*) and $x:result('err') instance of map(*)"/>            
+        </x:scenario>
+        <x:scenario label="Empty sequence">
+            <x:context mode="o:combine-elements" select="$ov:combine-merge">
+                <x:param name="elements" select="()"/>
+            </x:context>
+            <x:expect label="Nothing" select="()"/>
+        </x:scenario>
+    </x:scenario>
+    
+    <x:scenario label="Tests for match=catalog[merge/combine/@method='use-first'] priority=10 mode=o:combine-elements template">
+        <x:scenario label="Elements of same kind with duplicate id but distinct opr:id">
+            <x:context mode="o:combine-elements" select="$ov:combine-use-first">
+                <x:param name="elements" as="element()+" select="//o:control">
+                    <selection>
+                        <control id="a" opr:id="a"><title>Control A</title></control>
+                        <control id="a" opr:id="a1"><title>Control A1</title></control>
+                    </selection>
+                </x:param>
+            </x:context>
+            <x:expect label="First element">
+                <control id="a">
+                    <title>Control A</title>
+                </control>
+            </x:expect>
+        </x:scenario>
+        <x:scenario label="Elements of same kind with duplicate identifier">
+            <x:context mode="o:combine-elements" select="$ov:combine-use-first">
+                <x:param name="elements" as="element()+" select="//o:control">
+                    <selection>
+                        <control id="a" attr="val"><title>Control A</title></control>
+                        <control id="b"><title>Control B</title></control>
+                        <control id="a" attr1="val1"><title>Control A1</title></control>
+                    </selection>
+                </x:param>
+            </x:context>
+            <x:expect label="First element">
+                <control id="a" attr="val">
+                    <title>Control A</title>
+                </control>
+            </x:expect>
+            <x:expect label="No title from 2nd id=a control" test="empty(//title[.='Control  A1'])"/>
+            <x:expect label="No attr1 from 2nd id=a control" test="empty(//*[@attr1])"/>
+        </x:scenario>
+        <x:scenario label="Elements of different kinds">
+            <x:context mode="o:combine-elements" select="$ov:combine-use-first">
+                <x:param name="elements" as="element()+" select="//*:control">
+                    <selection>
+                        <control/>
+                        <control xmlns="foo"/>
+                    </selection>
+                </x:param>
+            </x:context>
+            <x:expect label="First element">
+                <control/>
+            </x:expect>
+        </x:scenario>
+        <x:scenario label="Empty sequence">
+            <x:context mode="o:combine-elements" select="$ov:combine-use-first">
+                <x:param name="elements" select="()"/>
+            </x:context>
+            <x:expect label="Nothing" select="()"/>
+        </x:scenario>
+    </x:scenario>
+
+    <x:scenario label="Tests for match=catalog priority=5 mode=o:combine-elements template">
+        <x:scenario label="Elements of same kind with duplicate id but distinct opr:id">
+            <x:context mode="o:combine-elements" select="$ov:combine-keep">
+                <x:param name="elements" as="element()+" select="//o:control">
+                    <selection>
+                        <control id="a" opr:id="a"><title>Control A</title></control>
+                        <control id="a" opr:id="a1"><title>Control A1</title></control>
+                    </selection>
+                </x:param>
+            </x:context>
+            <x:expect label="All elements">
+                <control id="a"><title>Control A</title></control>
+                <control id="a"><title>Control A1</title></control>
+            </x:expect>
+        </x:scenario>
+        <x:scenario label="Elements of same kind with duplicate identifier">
+            <x:context mode="o:combine-elements" select="$ov:combine-keep">
+                <x:param name="elements" as="element()+" select="//o:control">
+                    <selection>
+                        <control id="a" attr="val"><title>Control A</title></control>
+                        <control id="b"><title>Control B</title></control>
+                        <control id="a" attr1="val1"><title>Control A1</title></control>
+                    </selection>
+                </x:param>
+            </x:context>
+            <x:expect label="All elements">
+                <control id="a" attr="val"><title>Control A</title></control>
+                <control id="b"><title>Control B</title></control>
+                <control id="a" attr1="val1"><title>Control A1</title></control>
+            </x:expect>
+        </x:scenario>
+        <x:scenario label="Elements of different kinds">
+            <x:context mode="o:combine-elements" select="$ov:combine-keep">
+                <x:param name="elements" as="element()+" select="//*:control">
+                    <selection>
+                        <control/>
+                        <control xmlns="foo"/>
+                    </selection>
+                </x:param>
+            </x:context>
+            <x:expect label="All elements">
+                <control/>
+                <control xmlns="foo"/>
+            </x:expect>
+        </x:scenario>
+        <x:scenario label="Empty sequence">
+            <x:context mode="o:combine-elements" select="$ov:combine-keep">
+                <x:param name="elements" select="()"/>
+            </x:context>
+            <x:expect label="Nothing" select="()"/>
+        </x:scenario>
+    </x:scenario>
+
+</x:description>
diff --git a/src/utils/util/resolver-pipeline/testing/3_merged/merge-custom.xspec b/src/utils/util/resolver-pipeline/testing/3_merged/merge-custom.xspec
index 10ec033a70..4cf7ba997a 100644
--- a/src/utils/util/resolver-pipeline/testing/3_merged/merge-custom.xspec
+++ b/src/utils/util/resolver-pipeline/testing/3_merged/merge-custom.xspec
@@ -1,28 +1,16 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <x:description xmlns="http://csrc.nist.gov/ns/oscal/1.0"
-    xmlns:x="http://www.jenitennison.com/xslt/xspec"
+    xmlns:o="http://csrc.nist.gov/ns/oscal/1.0"
     xmlns:opr="http://csrc.nist.gov/ns/oscal/profile-resolution"
+    xmlns:ov="http://csrc.nist.gov/ns/oscal/test/variable"
+    xmlns:x="http://www.jenitennison.com/xslt/xspec"
     stylesheet="../../oscal-profile-resolve-merge.xsl">
 
-    <!-- Still needing unit tests
-      more elaborated merge scenarios
-      different selections and sorting
-      different rules on control/parameter merging using combine @method=keep|use-first|merge
-      -->
-
-    <x:scenario label="Base">
-        <x:context>
-            <catalog/>
-        </x:context>
-
-        <x:expect label="profile becomes catalog">
-            <catalog/>
-        </x:expect>
-    </x:scenario>
-    <x:scenario label="Single import, custom structure">
-        <x:context>
-            <catalog>
-                <selection uuid="xyz-tiny_catalog">
+    <x:scenario label="Tests for match=catalog[exists(merge/custom)] priority=13 template">
+        <x:scenario label="Single import, custom structure">
+            <x:context>
+                <catalog uuid="xyz-tiny_catalog">
+                    <selection uuid="xyz-tiny_catalog_selection">
                         <group id="x">
                             <title>Group X of XYZ</title>
                             <control id="x1" opr:id="xyz-tiny_catalog#x1"><title>Control X1</title></control>
@@ -49,7 +37,7 @@
                     </selection>
                     <merge>
                         <custom>
-                            <group>
+                            <group id="g1">
                                 <title>New Group 1</title>
                                 <insert-controls>
                                     <include-controls>
@@ -59,8 +47,8 @@
                                     </include-controls>
                                 </insert-controls>
                             </group>
-                            <group>
-                                <title>New Group 1</title>
+                            <group id="g2">
+                                <title>New Group 2</title>
                                 <insert-controls>
                                     <include-controls>
                                         <with-id>x2</with-id>
@@ -71,93 +59,577 @@
                             </group>
                         </custom>
                     </merge>
-            </catalog>
-        </x:context>
-        <x:expect label="New groups for XYZ 1 and 2">
-            <catalog>
-                <group>
-                    <title>New Group 1</title>
-                    <control id="x1"><title>Control X1</title></control>
-                    <control id="y1"><title>Control Y1</title></control>
-                    <control id="z1"><title>Control Z1</title></control>
-                </group>
-                <group>
-                    <title>New Group 1</title>
-                    <control id="x2"><title>Control X2</title></control>
-                    <control id="y2"><title>Control Y2</title></control>
-                    <control id="z2"><title>Control Z2</title></control>
-                </group>
-            </catalog>
-        </x:expect>
+                </catalog>
+            </x:context>
+            <x:expect label="Catalog with its attributes, and result of processing merge/custom">
+                <catalog uuid="xyz-tiny_catalog">
+                    <group id="g1">...</group>
+                    <group id="g2">...</group>
+                </catalog>
+            </x:expect>
+        </x:scenario>
     </x:scenario>
 
-    <x:scenario label="Parallel imports, no merge, keeping all">
-        <x:context>
-            <catalog>
-                <selection uuid="xyz-tiny_catalog">
-                    <group id="x">
-                        <title>Group X of XYZ</title>
-                        <control id="x1" opr:id="xyz-tiny_catalog#x1"><title>Control X1</title></control>
+    <x:scenario label="Tests for match=custom mode=o:custom-merge template">
+        <x:scenario label="Basic structure">
+            <x:context mode="o:custom-merge">
+                <custom>
+                    <foo/>
+                </custom>
+            </x:context>
+            <x:expect label="Processed child without custom wrapper tags">
+                <foo/>
+            </x:expect>
+        </x:scenario>
+        <x:scenario label="Test behavior of custom groups">
+            <x:scenario label="Single import with groups, merged into custom groups">
+                <x:context mode="o:custom-merge" select="//o:custom">
+                    <catalog uuid="xyz-tiny_catalog">
+                        <selection uuid="xyz-tiny_catalog_selection">
+                            <group id="x">
+                                <title>Group X of XYZ</title>
+                                <control id="x1" opr:id="xyz-tiny_catalog#x1"><title>Control X1</title></control>
+                                <control id="x2" opr:id="xyz-tiny_catalog#x2"><title>Control X2</title></control>
+                                <control id="x3" opr:id="xyz-tiny_catalog#x3"><title>Control X3</title></control>
+                            </group>
+                            <group id="y">
+                                <title>Group Y of XYZ</title>
+                                <control id="y1" opr:id="xyz-tiny_catalog#y1"><title>Control Y1</title></control>
+                                <control id="y2" opr:id="xyz-tiny_catalog#y2"><title>Control Y2</title></control>
+                                <control id="y3" opr:id="xyz-tiny_catalog#y3"><title>Control Y3</title></control>
+                            </group>
+                            <group id="z">
+                                <title>Group Z of XYZ</title>
+                                <control id="z1" opr:id="xyz-tiny_catalog#z1"><title>Control Z1</title></control>
+                                <control id="z2" opr:id="xyz-tiny_catalog#z2"><title>Control Z2</title></control>
+                                <control id="z3" opr:id="xyz-tiny_catalog#z3"><title>Control Z3</title>
+                                    <control id="z3.a" opr:id="xyz-tiny_catalog#z3.a"><title>Control Z3-A</title>
+                                        <control id="z3.a-1" opr:id="xyz-tiny_catalog#z3.a-1">
+                                            <title>Control Z3-A-1</title></control>
+                                    </control>
+                                </control>
+                            </group>
+                        </selection>
+                        <merge>
+                            <custom>
+                                <group id="g1">
+                                    <title>New Group 1</title>
+                                    <insert-controls>
+                                        <include-controls>
+                                            <with-id>x1</with-id>
+                                            <with-id>y1</with-id>
+                                            <with-id>z1</with-id>
+                                        </include-controls>
+                                    </insert-controls>
+                                </group>
+                                <group id="g2">
+                                    <title>New Group 2</title>
+                                    <insert-controls>
+                                        <include-controls>
+                                            <with-id>x2</with-id>
+                                            <with-id>y2</with-id>
+                                            <with-id>z2</with-id>
+                                        </include-controls>
+                                    </insert-controls>
+                                </group>
+                            </custom>
+                        </merge>
+                    </catalog>
+                </x:context>
+                <x:expect label="New groups for XYZ 1 and 2">
+                    <group id="g1">
+                        <title>New Group 1</title>
+                        <control id="x1"><title>Control X1</title></control>
+                        <control id="y1"><title>Control Y1</title></control>
+                        <control id="z1"><title>Control Z1</title></control>
                     </group>
-                    <group id="z">
-                        <title>Group Z of XYZ</title>
-                        <control id="z1" opr:id="xyz-tiny_catalog#z1"><title>Control Z1</title></control>
-                        <control id="z3" opr:id="xyz-tiny_catalog#z3"><title>Control Z3</title>
-                            <control id="z3.a" opr:id="xyz-tiny_catalog#z3.a"><title>Control Z3-A</title>
-                                <control id="z3.a-1" opr:id="xyz-tiny_catalog#z3.a-1"><title>Control Z3-A-1</title></control>
+                    <group id="g2">
+                        <title>New Group 2</title>
+                        <control id="x2"><title>Control X2</title></control>
+                        <control id="y2"><title>Control Y2</title></control>
+                        <control id="z2"><title>Control Z2</title></control>
+                    </group>
+                </x:expect>
+            </x:scenario>
+            <x:scenario label="Multiple imports with different group structure">
+                <x:context mode="o:custom-merge" select="//o:custom">
+                    <catalog uuid="xyz-tiny_catalog">
+                        <selection uuid="x_selection">
+                            <group id="x">
+                                <title>Group X of XYZ</title>
+                                <control id="x1" opr:id="xyz-tiny_catalog#x1"><title>Control X1</title></control>
+                                <control id="x2" opr:id="xyz-tiny_catalog#x2"><title>Control X2</title></control>
+                                <control id="x3" opr:id="xyz-tiny_catalog#x3"><title>Control X3</title></control>
+                            </group>
+                        </selection>
+                        <selection uuid="y_selection">
+                            <group id="parent">
+                                <title>Parent of Group Y</title>
+                                <group id="y">
+                                    <title>Group Y of XYZ</title>
+                                    <control id="y1" opr:id="xyz-tiny_catalog#y1"><title>Control Y1</title></control>
+                                    <control id="y2" opr:id="xyz-tiny_catalog#y2"><title>Control Y2</title></control>
+                                    <control id="y3" opr:id="xyz-tiny_catalog#y3"><title>Control Y3</title></control>
+                                </group>
+                            </group>
+                        </selection>
+                        <selection uuid="z:selection">
+                            <control id="z1" opr:id="xyz-tiny_catalog#z1"><title>Control Z1</title></control>
+                            <control id="z2" opr:id="xyz-tiny_catalog#z2"><title>Control Z2</title></control>
+                            <control id="z3" opr:id="xyz-tiny_catalog#z3"><title>Control Z3</title>
+                                <control id="z3.a" opr:id="xyz-tiny_catalog#z3.a"><title>Control Z3-A</title>
+                                    <control id="z3.a-1" opr:id="xyz-tiny_catalog#z3.a-1">
+                                        <title>Control Z3-A-1</title></control>
+                                </control>
                             </control>
-                        </control>
+                        </selection>
+                        <merge>
+                            <custom>
+                                <group id="g1">
+                                    <title>New Group 1</title>
+                                    <insert-controls>
+                                        <include-controls>
+                                            <with-id>x1</with-id>
+                                            <with-id>y1</with-id>
+                                            <with-id>z1</with-id>
+                                        </include-controls>
+                                    </insert-controls>
+                                </group>
+                                <group id="g2">
+                                    <title>New Group 2</title>
+                                    <insert-controls>
+                                        <include-controls>
+                                            <with-id>x2</with-id>
+                                            <with-id>y2</with-id>
+                                            <with-id>z2</with-id>
+                                        </include-controls>
+                                    </insert-controls>
+                                </group>
+                            </custom>
+                        </merge>
+                    </catalog>
+                </x:context>
+                <x:expect label="New groups for XYZ 1 and 2">
+                    <group id="g1">
+                        <title>New Group 1</title>
+                        <control id="x1"><title>Control X1</title></control>
+                        <control id="y1"><title>Control Y1</title></control>
+                        <control id="z1"><title>Control Z1</title></control>
                     </group>
-                </selection>
-                <selection uuid="xyz-tiny_catalog">
-                    <group id="x">
-                        <title>Group X of XYZ</title>
-                        <control id="x1" opr:id="xyz-tiny_catalog#x1">
-                            <title>Control X1</title>
-                            <prop value="modified property" name="mod"/>
-                        </control>
-                        <control id="x2" opr:id="xyz-tiny_catalog#x2"><title>Control X2</title></control>
+                    <group id="g2">
+                        <title>New Group 2</title>
+                        <control id="x2"><title>Control X2</title></control>
+                        <control id="y2"><title>Control Y2</title></control>
+                        <control id="z2"><title>Control Z2</title></control>
                     </group>
-                    <group id="y">
-                        <title>Group Y of XYZ</title>
-                        <control id="y1" opr:id="xyz-tiny_catalog#y1"><title>Control Y1</title></control>
-                        <control id="y2" opr:id="xyz-tiny_catalog#y2"><title>Control Y2</title></control>
-                        <control id="y3" opr:id="xyz-tiny_catalog#y3"><title>Control Y3</title></control>
+                </x:expect>
+            </x:scenario>
+            <x:scenario label="Custom groups using include-all, exclude-controls, and insert-controls">
+                <x:context mode="o:custom-merge" select="//o:custom">
+                    <catalog uuid="xyz-tiny_catalog">
+                        <selection uuid="xyz-tiny_catalog_selection">
+                            <control id="x1" opr:id="xyz-tiny_catalog#x1"><title>Control X1</title></control>
+                            <control id="x2" opr:id="xyz-tiny_catalog#x2"><title>Control X2</title></control>
+                            <control id="x3" opr:id="xyz-tiny_catalog#x3"><title>Control X3</title></control>
+                        </selection>
+                        <merge>
+                            <custom>
+                                <group>
+                                    <title>Group A</title>
+                                    <insert-controls>
+                                        <include-all/>
+                                        <exclude-controls>
+                                            <with-id>x2</with-id>
+                                        </exclude-controls>
+                                    </insert-controls>
+                                </group>
+                                <group>
+                                    <title>Group B</title>
+                                    <insert-controls>
+                                        <include-controls>
+                                            <with-id>x2</with-id>
+                                        </include-controls>
+                                    </insert-controls>
+                                </group>
+                            </custom>
+                        </merge>
+                    </catalog>
+                </x:context>
+                <x:expect label="Group A with controls x1 and x3" test="/o:group[1]">
+                    <group>
+                        <title>Group A</title>
+                        <control id="x1"><title>Control X1</title></control>
+                        <control id="x3"><title>Control X3</title></control>
                     </group>
-                    <group id="z">
-                        <title>Group Z of XYZ</title>
-                        <control id="z3" opr:id="xyz-tiny_catalog#z3"><title>Control Z3</title>
-                            <control id="z3.a" opr:id="xyz-tiny_catalog#z3.a"><title>Control Z3-A</title>
-                                <control id="z3.a-1" opr:id="xyz-tiny_catalog#z3.a-1"><title>Control Z3-A-1</title></control>
-                            </control>
-                        </control>
+                </x:expect>
+                <x:expect label="Group B with control x2" test="/o:group[2]">
+                    <group>
+                        <title>Group B</title>
+                        <control id="x2"><title>Control X2</title></control>
                     </group>
+                </x:expect>
+            </x:scenario>
+            <x:scenario label="Nested custom groups">
+                <x:context mode="o:custom-merge" select="//o:custom">
+                    <catalog uuid="xyz-tiny_catalog">
+                        <selection uuid="xyz-tiny_catalog_selection">
+                            <control id="x1" opr:id="xyz-tiny_catalog#x1"><title>Control X1</title></control>
+                            <control id="x2" opr:id="xyz-tiny_catalog#x2"><title>Control X2</title></control>
+                            <control id="x3" opr:id="xyz-tiny_catalog#x3"><title>Control X3</title></control>
+                        </selection>
+                        <merge>
+                            <custom>
+                                <group id="a">
+                                    <title>Group A</title>
+                                    <group id="a.1">
+                                        <title>Group A.1</title>
+                                        <insert-controls>
+                                            <include-controls>
+                                                <with-id>x2</with-id>
+                                                <with-id>nonexistent</with-id>
+                                            </include-controls>
+                                        </insert-controls>
+                                    </group>
+                                </group>
+                                <group id="b">
+                                    <title>Group B</title>
+                                    <group id="b.1">
+                                        <title>Group B.1</title>
+                                        <insert-controls>
+                                            <include-controls>
+                                                <matching>q*</matching>
+                                            </include-controls>
+                                        </insert-controls>
+                                    </group>
+                                </group>
+                            </custom>
+                        </merge>
+                    </catalog>
+                </x:context>
+                <x:expect label="Group A containing group A.1 containing control x2" test="/o:group[1]">
+                    <group id="a">
+                        <title>Group A</title>
+                        <group id="a.1">
+                            <title>Group A.1</title>
+                            <control id="x2"><title>Control X2</title></control>
+                        </group>
+                    </group>
+                </x:expect>
+                <x:expect label="Group B containing group B.1 containing no controls" test="/o:group[2]">
+                    <group id="b">
+                        <title>Group B</title>
+                        <group id="b.1">
+                            <title>Group B.1</title>
+                        </group>
+                    </group>
+                </x:expect>
+            </x:scenario>
+        </x:scenario>
+    </x:scenario>
+
+    <x:scenario label="Tests for match=insert-controls mode=o:custom-merge template">
+        <x:scenario label="include-all followed by exclude-controls">
+            <x:context mode="o:custom-merge" select="//o:insert-controls">
+                <catalog uuid="xyz-tiny_catalog">
+                    <selection uuid="xyz-tiny_catalog">
+                        <control id="x1" opr:id="xyz-tiny_catalog#x1"><title>Control X1</title></control>
+                        <control id="x2" opr:id="xyz-tiny_catalog#x2"><title>Control X2</title></control>
+                        <control id="x3" opr:id="xyz-tiny_catalog#x3"><title>Control X3</title></control>
+                    </selection>
+                    <merge>
+                        <custom>
+                            <insert-controls>
+                                <include-all/>
+                                <exclude-controls>
+                                    <with-id>x2</with-id>
+                                    <matching pattern="*1"/>
+                                </exclude-controls>
+                            </insert-controls>
+                        </custom>
+                    </merge>
+                </catalog>
+            </x:context>
+            <x:expect label="Control x3 because x1 and x2 were excluded">
+                <control id="x3"><title>Control X3</title></control>                
+            </x:expect>
+        </x:scenario>
+        <x:scenario label="insert-controls looking for controls not in catalog/selection">
+            <x:context mode="o:custom-merge" select="//o:custom">
+                <catalog uuid="xyz-tiny_catalog">
+                    <selection uuid="xyz-tiny_catalog_selection">
+                        <control id="x1" opr:id="xyz-tiny_catalog#x1"><title>Control X1</title></control>
+                        <control id="x2" opr:id="xyz-tiny_catalog#x2"><title>Control X2</title></control>
+                        <control id="x3" opr:id="xyz-tiny_catalog#x3"><title>Control X3</title></control>
+                    </selection>
+                    <merge>
+                        <custom>
+                            <insert-controls>
+                                <include-controls>
+                                    <matching pattern="nonexistent*"/>
+                                    <with-id>nonexistent</with-id>
+                                </include-controls>
+                            </insert-controls>
+                        </custom>
+                    </merge>
+                </catalog>
+            </x:context>
+            <x:expect label="Nothing" select="()"/>
+        </x:scenario>
+        <x:scenario label="Descending order by control ID">
+            <x:variable name="ov:order" select="'descending'"/>
+            <x:like label="SHARED: Context with placeholder for insert-controls order"/>
+            <x:expect label="Controls x3, x1, and ax2 in that order">
+                <control id="x3"><title>Control X3</title></control>
+                <control id="x1"><title>Control X1</title></control>
+                <control id="ax2"><title>Control X2</title></control>
+            </x:expect>
+        </x:scenario>
+        <x:scenario label="Ascending by control ID">
+            <x:variable name="ov:order" select="'ascending'"/>
+            <x:like label="SHARED: Context with placeholder for insert-controls order"/>
+            <x:expect label="Controls ax2, x1, and x3 in that order">
+                <control id="ax2"><title>Control X2</title></control>
+                <control id="x1"><title>Control X1</title></control>
+                <control id="x3"><title>Control X3</title></control>                
+            </x:expect>
+        </x:scenario>
+        <x:scenario label="Keep order from catalog">
+            <!-- Note: Output of selection phase XSLT has catalog/selection that
+                reflects order of controls in input catalog. For tests that confirm
+                this behavior, search select.xspec for "Order of controls in output". -->
+            <x:variable name="ov:order" select="'keep'"/>
+            <x:like label="SHARED: Context with placeholder for insert-controls order"/>
+            <x:expect label="Controls x1, ax2, and x3 in that order">
+                <control id="x1"><title>Control X1</title></control>
+                <control id="ax2"><title>Control X2</title></control>
+                <control id="x3"><title>Control X3</title></control>                
+            </x:expect>
+        </x:scenario>
+        <x:scenario label="Empty string for order attribute (behaves like order=keep)">
+            <x:variable name="ov:order" select="''"/>
+            <x:like label="SHARED: Context with placeholder for insert-controls order"/>
+            <x:expect label="Controls x1, ax2, and x3 in that order">
+                <control id="x1"><title>Control X1</title></control>
+                <control id="ax2"><title>Control X2</title></control>
+                <control id="x3"><title>Control X3</title></control>
+            </x:expect>
+        </x:scenario>
+    </x:scenario>
+
+    <x:scenario shared="yes" label="SHARED: Context with placeholder for insert-controls order">
+        <x:context mode="o:custom-merge" select="//o:insert-controls">
+            <catalog uuid="xyz-tiny_catalog">
+                <selection uuid="xyz-tiny_catalog_selection">
+                    <control id="x1" opr:id="xyz-tiny_catalog#x1"><title>Control X1</title></control>
+                    <control id="ax2" opr:id="xyz-tiny_catalog#ax2"><title>Control X2</title></control>
+                    <control id="x3" opr:id="xyz-tiny_catalog#x3"><title>Control X3</title></control>
                 </selection>
+                <merge>
+                    <custom>
+                        <insert-controls order="{$ov:order}">
+                            <include-controls><!-- Order of with-id elements does not matter. -->
+                                <with-id>x1</with-id>
+                                <with-id>x3</with-id>
+                                <with-id>ax2</with-id>
+                            </include-controls>
+                        </insert-controls>                            
+                    </custom>
+                </merge>
             </catalog>
         </x:context>
-        <x:expect label="XYZ catalog twice, flat, with clashing controls">
-            <catalog>
-                <control id="x1"><title>Control X1</title></control>
-                <control id="z1"><title>Control Z1</title></control>
-                <control id="z3"><title>Control Z3</title>
-                    <control id="z3.a"><title>Control Z3-A</title>
-                        <control id="z3.a-1"><title>Control Z3-A-1</title></control>
-                    </control>
-                </control>
-                <control id="x1">
-                    <title>Control X1</title>
-                    <prop value="modified property" name="mod"/>
+    </x:scenario>
+
+    <x:scenario label="Tests for match=include-all | include-controls mode=o:custom-merge template">
+        <!-- Template shares code with selection phase, which is tested in select.xspec.
+            These scenarios merely spot-check. -->
+        <x:scenario label="include-controls matches something">
+            <x:context mode="o:custom-merge" select="//o:include-controls">
+                <catalog uuid="xyz-tiny_catalog">
+                    <selection>
+                        <control id="a1"/>
+                        <control id="a2"/>
+                    </selection>
+                    <merge>
+                        <custom>
+                            <insert-controls>
+                                <include-controls>
+                                    <with-id>a1</with-id>
+                                </include-controls>
+                            </insert-controls>
+                        </custom>
+                    </merge>
+                </catalog>
+            </x:context>
+            <x:expect label="Specified controls">
+                <control id="a1"/>
+            </x:expect>
+        </x:scenario>
+        <x:scenario label="include-controls does not match anything">
+            <x:context mode="o:custom-merge" select="//o:include-controls">
+                <catalog uuid="xyz-tiny_catalog">
+                    <selection>
+                        <control id="a1"/>
+                    </selection>
+                    <merge>
+                        <custom>
+                            <insert-controls>
+                                <include-controls>
+                                    <with-id>nonexistent</with-id>
+                                </include-controls>
+                            </insert-controls>
+                        </custom>
+                    </merge>
+                </catalog>
+            </x:context>
+            <x:expect label="Nothing" select="()"/>
+        </x:scenario>
+        <x:scenario label="include-all with no exclusions">
+            <x:context mode="o:custom-merge" select="//o:include-all">
+                <catalog uuid="xyz-tiny_catalog">
+                    <selection>
+                        <control id="a1"/>
+                        <control id="a2"/>
+                    </selection>
+                    <merge>
+                        <custom>
+                            <insert-controls>
+                                <include-all/>
+                            </insert-controls>
+                        </custom>
+                    </merge>
+                </catalog>
+            </x:context>
+            <x:expect label="All controls">
+                <control id="a1"/>
+                <control id="a2"/>
+            </x:expect>
+        </x:scenario>
+        <x:scenario label="include-all with exclusions">
+            <x:context mode="o:custom-merge" select="//o:include-all">
+                <catalog uuid="xyz-tiny_catalog">
+                    <selection>
+                        <control id="a1"/>
+                        <control id="a2"/>
+                    </selection>
+                    <merge>
+                        <custom>
+                            <insert-controls>
+                                <include-all/>
+                                <exclude-controls>
+                                    <matching pattern="a*"/>
+                                </exclude-controls>
+                            </insert-controls>
+                        </custom>
+                    </merge>
+                </catalog>
+            </x:context>
+            <x:expect label="All controls not excluded - in this case, nothing"
+                select="()"/>
+        </x:scenario>
+        <x:scenario label="include-controls without child controls (default choice)">
+            <x:context mode="o:custom-merge" select="//o:include-controls">
+                <catalog uuid="xyz-tiny_catalog">
+                    <selection>
+                        <control id="a1">
+                            <control id="a1.1"/>
+                        </control>
+                    </selection>
+                    <merge>
+                        <custom>
+                            <insert-controls>
+                                <include-controls with-child-controls="no">
+                                    <with-id>a1</with-id>
+                                </include-controls>
+                            </insert-controls>
+                        </custom>
+                    </merge>
+                </catalog>
+            </x:context>
+            <x:expect label="Parent control without child control">
+                <control id="a1"/>
+            </x:expect>
+        </x:scenario>
+        <x:scenario label="include-controls with child controls (nondefault choice)">
+            <x:context mode="o:custom-merge" select="//o:include-controls">
+                <catalog uuid="xyz-tiny_catalog">
+                    <selection>
+                        <control id="a1">
+                            <control id="a1.1"/>
+                        </control>
+                    </selection>
+                    <merge>
+                        <custom>
+                            <insert-controls>
+                                <include-controls with-child-controls="yes">
+                                    <with-id>a1</with-id>
+                                </include-controls>
+                            </insert-controls>
+                        </custom>
+                    </merge>
+                </catalog>
+            </x:context>
+            <x:expect label="Parent control with child control">
+                <control id="a1">
+                    <control id="a1.1"/>
                 </control>
-                <control id="x2"><title>Control X2</title></control>
-                <control id="y1"><title>Control Y1</title></control>
-                <control id="y2"><title>Control Y2</title></control>
-                <control id="y3"><title>Control Y3</title></control>
-                <control id="z3"><title>Control Z3</title>
-                    <control id="z3.a"><title>Control Z3-A</title>
-                        <control id="z3.a-1"><title>Control Z3-A-1</title></control>
-                    </control>
+            </x:expect>
+        </x:scenario>
+        <x:scenario label="include-controls with parent controls (default choice)">
+            <x:context mode="o:custom-merge" select="//o:include-controls">
+                <catalog uuid="xyz-tiny_catalog">
+                    <selection>
+                        <control id="a1">
+                            <control id="a1.1"/>
+                        </control>
+                    </selection>
+                    <merge>
+                        <custom>
+                            <insert-controls>
+                                <include-controls with-parent-controls="yes">
+                                    <with-id>a1.1</with-id>
+                                </include-controls>
+                            </insert-controls>
+                        </custom>
+                    </merge>
+                </catalog>
+            </x:context>
+            <x:expect label="Parent control with child">
+                <control id="a1">
+                    <control id="a1.1"/>
                 </control>
-            </catalog>
-        </x:expect>
+            </x:expect>
+        </x:scenario>
+        <x:scenario label="include-controls without parent controls (nondefault choice)">
+            <x:context mode="o:custom-merge" select="//o:include-controls">
+                <catalog uuid="xyz-tiny_catalog">
+                    <selection>
+                        <control id="a1">
+                            <control id="a1.1"/>
+                        </control>
+                    </selection>
+                    <merge>
+                        <custom>
+                            <insert-controls>
+                                <include-controls with-parent-controls="no">
+                                    <with-id>a1.1</with-id>
+                                </include-controls>
+                            </insert-controls>
+                        </custom>
+                    </merge>
+                </catalog>
+            </x:context>
+            <x:expect label="Child control without parent">
+                <control id="a1.1"/>
+            </x:expect>
+        </x:scenario>
+    </x:scenario>
+
+    <x:scenario label="Tests for match=exclude-controls mode=o:custom-merge template">
+        <x:context mode="o:custom-merge">
+            <exclude-controls>
+                <with-id>x1</with-id>
+            </exclude-controls>
+        </x:context>
+        <x:expect label="Nothing" select="()"/>
     </x:scenario>
 </x:description>
diff --git a/src/utils/util/resolver-pipeline/testing/3_merged/merge.xspec b/src/utils/util/resolver-pipeline/testing/3_merged/merge.xspec
index c4619ccbea..d9e44c873d 100644
--- a/src/utils/util/resolver-pipeline/testing/3_merged/merge.xspec
+++ b/src/utils/util/resolver-pipeline/testing/3_merged/merge.xspec
@@ -1,17 +1,57 @@
-<?xml version="1.0" encoding="UTF-8"?><x:description xmlns="http://csrc.nist.gov/ns/oscal/1.0" xmlns:x="http://www.jenitennison.com/xslt/xspec" xmlns:opr="http://csrc.nist.gov/ns/oscal/profile-resolution" stylesheet="../../oscal-profile-resolve-merge.xsl">
-    <x:scenario label="Base">
+<?xml version="1.0" encoding="UTF-8"?>
+<x:description xmlns="http://csrc.nist.gov/ns/oscal/1.0"
+    xmlns:o="http://csrc.nist.gov/ns/oscal/1.0"
+    xmlns:opr="http://csrc.nist.gov/ns/oscal/profile-resolution"
+    xmlns:ov="http://csrc.nist.gov/ns/oscal/xspec/variable"
+    xmlns:x="http://www.jenitennison.com/xslt/xspec"
+    stylesheet="../../oscal-profile-resolve-merge.xsl">
+
+    <x:scenario label="Tests for match='/ | * | @*' template for all modes">
+        <!-- Include wrapper in $ov:arbitrary-element to bypass match="/*" template. -->
+        <x:variable name="ov:arbitrary-element" as="element(arbitrary-element)" select="//arbitrary-element">
+            <some-wrapper>
+                <arbitrary-element xmlns="" arbitrary-attribute="val">text<child/></arbitrary-element>
+            </some-wrapper>
+        </x:variable>
+        <x:scenario label="Element">
+            <x:context select="$ov:arbitrary-element"/>
+            <x:expect label="Copy" select="$ov:arbitrary-element"/>
+        </x:scenario>
+        <x:scenario label="Attribute">
+            <x:context select="$ov:arbitrary-element/@arbitrary-attribute"/>
+            <x:expect label="Copy"
+                test="$x:result instance of attribute(arbitrary-attribute) and $x:result/string()='val'"/>
+        </x:scenario>
+    </x:scenario>
+
+
+    <x:scenario label="Test for match=/* priority=1 template, which should not be reached in practice">
         <x:context>
-            <catalog/>
+            <not-a-catalog/>
         </x:context>
+        <x:expect label="Nothing" select="()"/>
+    </x:scenario>
 
-        <x:expect label="profile becomes catalog">
-            <catalog/>
+    <x:scenario label="Test for match=catalog priority=2 template">
+        <!-- Context is a catalog with neither selection nor merge. -->
+        <x:context>
+            <catalog uuid="zzz">
+                <metadata/>
+            </catalog>
+        </x:context>
+        <x:expect label="Copy of catalog">
+            <catalog uuid="zzz">
+                <metadata/>
+            </catalog>
         </x:expect>
     </x:scenario>
-    <x:scenario label="Single import, no merge (flat)">
-        <x:context>
-            <catalog>
-                <selection uuid="xyz-tiny_catalog">
+
+    <x:scenario label="Tests for match=catalog[exists(selection)] priority=10 template">
+        <!-- Context is a catalog with at least one selection child but no merge child. -->
+        <x:scenario label="Single import, no merge (flat)">
+            <x:context>
+                <catalog>
+                    <selection uuid="xyz-tiny_catalog">
                         <group id="x">
                             <title>Group X of XYZ</title>
                             <control id="x1" opr:id="xyz-tiny_catalog#x1"><title>Control X1</title></control>
@@ -36,29 +76,206 @@
                             </control>
                         </group>
                     </selection>
-                <!-- no merge -->
-            </catalog>
-        </x:context>
-        <x:expect label="All XYZ controls, ungrouped">
-            <catalog>
-                <control id="x1"><title>Control X1</title></control>
-                <control id="x2"><title>Control X2</title></control>
-                <control id="x3"><title>Control X3</title></control>
-                <control id="y1"><title>Control Y1</title></control>
-                <control id="y2"><title>Control Y2</title></control>
-                <control id="y3"><title>Control Y3</title></control>
-                <control id="z1"><title>Control Z1</title></control>
-                <control id="z2"><title>Control Z2</title></control>
-                <control id="z3"><title>Control Z3</title>
-                    <control id="z3.a"><title>Control Z3-A</title>
-                        <control id="z3.a-1"><title>Control Z3-A-1</title></control>
+                    <!-- no merge -->
+                </catalog>
+            </x:context>
+            <x:expect label="All XYZ controls, ungrouped">
+                <catalog>
+                    <control id="x1"><title>Control X1</title></control>
+                    <control id="x2"><title>Control X2</title></control>
+                    <control id="x3"><title>Control X3</title></control>
+                    <control id="y1"><title>Control Y1</title></control>
+                    <control id="y2"><title>Control Y2</title></control>
+                    <control id="y3"><title>Control Y3</title></control>
+                    <control id="z1"><title>Control Z1</title></control>
+                    <control id="z2"><title>Control Z2</title></control>
+                    <control id="z3"><title>Control Z3</title>
+                        <control id="z3.a"><title>Control Z3-A</title>
+                            <control id="z3.a-1"><title>Control Z3-A-1</title></control>
+                        </control>
                     </control>
-                </control>
-            </catalog>
-        </x:expect>
+                </catalog>
+            </x:expect>
+        </x:scenario>
+        <x:scenario label="Parallel imports, no merge, keeping all">
+            <x:context>
+                <catalog>
+                    <selection uuid="xyz-tiny_catalog">
+                        <group id="x">
+                            <title>Group X of XYZ</title>
+                            <control id="x1" opr:id="xyz-tiny_catalog#x1"><title>Control X1</title></control>
+                        </group>
+                        <group id="z">
+                            <title>Group Z of XYZ</title>
+                            <control id="z1" opr:id="xyz-tiny_catalog#z1"><title>Control Z1</title></control>
+                            <control id="z3" opr:id="xyz-tiny_catalog#z3"><title>Control Z3</title>
+                                <control id="z3.a" opr:id="xyz-tiny_catalog#z3.a"><title>Control Z3-A</title>
+                                    <control id="z3.a-1" opr:id="xyz-tiny_catalog#z3.a-1"><title>Control Z3-A-1</title></control>
+                                </control>
+                            </control>
+                        </group>
+                    </selection>
+                    <selection uuid="xyz-tiny_catalog">
+                        <group id="x">
+                            <title>Group X of XYZ</title>
+                            <control id="x1" opr:id="xyz-tiny_catalog#x1">
+                                <title>Control X1</title>
+                                <prop value="modified property" name="mod"/>
+                            </control>
+                            <control id="x2" opr:id="xyz-tiny_catalog#x2"><title>Control X2</title></control>
+                        </group>
+                        <group id="y">
+                            <title>Group Y of XYZ</title>
+                            <control id="y1" opr:id="xyz-tiny_catalog#y1"><title>Control Y1</title></control>
+                            <control id="y2" opr:id="xyz-tiny_catalog#y2"><title>Control Y2</title></control>
+                            <control id="y3" opr:id="xyz-tiny_catalog#y3"><title>Control Y3</title></control>
+                        </group>
+                        <group id="z">
+                            <title>Group Z of XYZ</title>
+                            <control id="z3" opr:id="xyz-tiny_catalog#z3"><title>Control Z3</title>
+                                <control id="z3.a" opr:id="xyz-tiny_catalog#z3.a"><title>Control Z3-A</title>
+                                    <control id="z3.a-1" opr:id="xyz-tiny_catalog#z3.a-1"><title>Control Z3-A-1</title></control>
+                                </control>
+                            </control>
+                        </group>
+                    </selection>
+                    <!-- no merge -->
+                </catalog>
+            </x:context>
+            <x:expect label="XYZ catalog twice, flat, with clashing controls">
+                <catalog>
+                    <control id="x1"><title>Control X1</title></control>
+                    <control id="z1"><title>Control Z1</title></control>
+                    <control id="z3"><title>Control Z3</title>
+                        <control id="z3.a"><title>Control Z3-A</title>
+                            <control id="z3.a-1"><title>Control Z3-A-1</title></control>
+                        </control>
+                    </control>
+                    <control id="x1">
+                        <title>Control X1</title>
+                        <prop value="modified property" name="mod"/>
+                    </control>
+                    <control id="x2"><title>Control X2</title></control>
+                    <control id="y1"><title>Control Y1</title></control>
+                    <control id="y2"><title>Control Y2</title></control>
+                    <control id="y3"><title>Control Y3</title></control>
+                    <control id="z3"><title>Control Z3</title>
+                        <control id="z3.a"><title>Control Z3-A</title>
+                            <control id="z3.a-1"><title>Control Z3-A-1</title></control>
+                        </control>
+                    </control>
+                </catalog>
+            </x:expect>
+        </x:scenario>
+        <x:scenario label="Catalog with attribute, metadata, and modify child">
+            <x:context>
+                <catalog uuid="zzz">
+                    <metadata>
+                        <title>Test Profile</title>
+                        <last-modified>2019-11-13T12:41:07.061-05:00</last-modified>
+                        <version>1.3</version>
+                        <oscal-version>1.0.2</oscal-version>
+                        <prop name="resolution-tool" value="OSCAL Profile Resolver XSLT Pipeline OPRXP" />
+                        <link href="urn:UNKNOWN" rel="source-profile" />
+                    </metadata>
+                    <selection uuid="xyz-tiny_catalog">
+                        <control id="x1"><title>Control X1</title></control>
+                    </selection>
+                    <!-- no merge -->
+                    <modify>
+                        <set-parameter param-id="a1_prm1">
+                            <constraint>
+                                <description>
+                                    <p>at least every 3 years</p>
+                                </description>
+                            </constraint>
+                        </set-parameter>
+                    </modify>
+                </catalog>
+            </x:context>
+            <x:expect label="Output includes catalog attribute, metadata, and modify child">
+                <catalog uuid="zzz">
+                    <metadata>
+                        <title>Test Profile</title>
+                        <last-modified>2019-11-13T12:41:07.061-05:00</last-modified>
+                        <version>1.3</version>
+                        <oscal-version>1.0.2</oscal-version>
+                        <prop name="resolution-tool" value="OSCAL Profile Resolver XSLT Pipeline OPRXP" />
+                        <link href="urn:UNKNOWN" rel="source-profile" />
+                    </metadata>
+                    <control id="x1"><title>Control X1</title></control>
+                    <modify>
+                        <set-parameter param-id="a1_prm1">
+                            <constraint>
+                                <description>
+                                    <p>at least every 3 years</p>
+                                </description>
+                            </constraint>
+                        </set-parameter>
+                    </modify>
+                </catalog>
+            </x:expect>
+        </x:scenario>
+        <x:scenario label="Catalog with back matter inside and outside selection">
+            <x:context>
+                <catalog uuid="zzz">
+                    <selection uuid="xyz-tiny_catalog">
+                        <control id="x1"><title>Control X1</title></control>
+                        <back-matter>
+                            <resource uuid="0050231f-4fd0-43d6-8fa0-431367cd83e2">
+                                <title>Ref BBB</title>
+                                <citation>
+                                    <text>Bbb bbbbb Bbb b.</text>
+                                </citation>
+                                <rlink href="bbb.html"/>
+                            </resource>
+                        </back-matter>
+                    </selection>
+                    <!-- no merge -->
+                    <back-matter>
+                        <resource uuid="0050231f-4fd0-43d6-8fa0-431367cd83e1">
+                            <title>Ref AAA</title>
+                            <citation>
+                                <text>Aaaa aaaa aaaa</text>
+                            </citation>
+                            <rlink href="aaa.html"/>
+                        </resource>
+                    </back-matter>
+                </catalog>
+            </x:context>
+            <x:expect label="Output includes consolidated back matter">
+                <catalog uuid="zzz">
+                    <control id="x1"><title>Control X1</title></control>
+                    <back-matter>
+                        <resource uuid="0050231f-4fd0-43d6-8fa0-431367cd83e2">
+                            <title>Ref BBB</title>
+                            <citation>
+                                <text>Bbb bbbbb Bbb b.</text>
+                            </citation>
+                            <rlink href="bbb.html"/>
+                        </resource>
+                        <resource uuid="0050231f-4fd0-43d6-8fa0-431367cd83e1">
+                            <title>Ref AAA</title>
+                            <citation>
+                                <text>Aaaa aaaa aaaa</text>
+                            </citation>
+                            <rlink href="aaa.html"/>
+                        </resource>
+                    </back-matter>
+                </catalog>
+            </x:expect>
+        </x:scenario>
+        <x:scenario label="as-is element appears but content is not true">
+            <x:variable name="ov:as-is-content">0</x:variable>
+            <x:like label="SHARED: as-is element with placeholder for content"/>
+        </x:scenario>
+        <x:scenario label="as-is element appears but has no content">
+            <x:variable name="ov:as-is-content"/>
+            <x:like label="SHARED: as-is element with placeholder for content"/>
+        </x:scenario>
     </x:scenario>
 
-    <x:scenario label="Parallel imports, no merge, keeping all">
+    <x:scenario shared="yes" label="SHARED: as-is element with placeholder for content">
         <x:context>
             <catalog>
                 <selection uuid="xyz-tiny_catalog">
@@ -66,65 +283,450 @@
                         <title>Group X of XYZ</title>
                         <control id="x1" opr:id="xyz-tiny_catalog#x1"><title>Control X1</title></control>
                     </group>
-                    <group id="z">
-                        <title>Group Z of XYZ</title>
-                        <control id="z1" opr:id="xyz-tiny_catalog#z1"><title>Control Z1</title></control>
-                        <control id="z3" opr:id="xyz-tiny_catalog#z3"><title>Control Z3</title>
-                            <control id="z3.a" opr:id="xyz-tiny_catalog#z3.a"><title>Control Z3-A</title>
-                                <control id="z3.a-1" opr:id="xyz-tiny_catalog#z3.a-1"><title>Control Z3-A-1</title></control>
-                            </control>
-                        </control>
-                    </group>
-                </selection>
-                <selection uuid="xyz-tiny_catalog">
-                    <group id="x">
-                        <title>Group X of XYZ</title>
-                        <control id="x1" opr:id="xyz-tiny_catalog#x1">
-                            <title>Control X1</title>
-                            <prop value="modified property" name="mod"/>
-                        </control>
-                        <control id="x2" opr:id="xyz-tiny_catalog#x2"><title>Control X2</title></control>
-                    </group>
                     <group id="y">
                         <title>Group Y of XYZ</title>
                         <control id="y1" opr:id="xyz-tiny_catalog#y1"><title>Control Y1</title></control>
-                        <control id="y2" opr:id="xyz-tiny_catalog#y2"><title>Control Y2</title></control>
-                        <control id="y3" opr:id="xyz-tiny_catalog#y3"><title>Control Y3</title></control>
-                    </group>
-                    <group id="z">
-                        <title>Group Z of XYZ</title>
-                        <control id="z3" opr:id="xyz-tiny_catalog#z3"><title>Control Z3</title>
-                            <control id="z3.a" opr:id="xyz-tiny_catalog#z3.a"><title>Control Z3-A</title>
-                                <control id="z3.a-1" opr:id="xyz-tiny_catalog#z3.a-1"><title>Control Z3-A-1</title></control>
-                            </control>
-                        </control>
                     </group>
                 </selection>
+                <merge>
+                    <as-is x:expand-text="true">{$ov:as-is-content}</as-is>
+                </merge>
             </catalog>
         </x:context>
-        <x:expect label="XYZ catalog twice, flat, with clashing controls">
+        <x:expect label="Flat structure, not grouped">
             <catalog>
                 <control id="x1"><title>Control X1</title></control>
-                <control id="z1"><title>Control Z1</title></control>
-                <control id="z3"><title>Control Z3</title>
-                    <control id="z3.a"><title>Control Z3-A</title>
-                        <control id="z3.a-1"><title>Control Z3-A-1</title></control>
-                    </control>
-                </control>
-                <control id="x1">
-                    <title>Control X1</title>
-                    <prop value="modified property" name="mod"/>
-                </control>
-                <control id="x2"><title>Control X2</title></control>
                 <control id="y1"><title>Control Y1</title></control>
-                <control id="y2"><title>Control Y2</title></control>
-                <control id="y3"><title>Control Y3</title></control>
-                <control id="z3"><title>Control Z3</title>
-                    <control id="z3.a"><title>Control Z3-A</title>
-                        <control id="z3.a-1"><title>Control Z3-A-1</title></control>
-                    </control>
-                </control>
             </catalog>
         </x:expect>
     </x:scenario>
+
+    <!-- Tests for match=catalog[merge/as-is=$true-content] priority=12 template are in merge-as-is.xspec -->
+    <!-- Tests for match=catalog[exists(merge/custom)] priority=13 template are in merge-custom.xspec -->
+
+    <x:scenario label="Tests for detect-multiple-structuring-directives template">
+        <x:scenario label="Error case: custom appears and as-is is true" catch="yes">
+            <x:context>
+                <catalog uuid="xyz-tiny_catalog">
+                    <merge>
+                        <custom/>
+                        <as-is>1</as-is>
+                    </merge>
+                </catalog>
+            </x:context>
+            <x:call template="detect-multiple-structuring-directives"/>
+            <x:expect label="Fatal XSLT error"
+                test="$x:result instance of map(*) and $x:result('err') instance of map(*)"/>            
+        </x:scenario>
+        <x:scenario label="Error case: custom appears and flat is true" catch="yes">
+            <x:context>
+                <catalog uuid="xyz-tiny_catalog">
+                    <merge>
+                        <custom/>
+                        <flat>true</flat>
+                    </merge>
+                </catalog>
+            </x:context>
+            <x:call template="detect-multiple-structuring-directives"/>
+            <x:expect label="Fatal XSLT error"
+                test="$x:result instance of map(*) and $x:result('err') instance of map(*)"/>            
+        </x:scenario>
+        <x:scenario label="Error case: as-is and flat are both true" catch="yes">  
+            <x:context>
+                <catalog>
+                    <merge>
+                        <flat>true</flat>
+                        <as-is>1</as-is>
+                    </merge>
+                </catalog>
+            </x:context>
+            <x:call template="detect-multiple-structuring-directives"/>
+            <x:expect label="Fatal XSLT error"
+                test="$x:result instance of map(*) and $x:result('err') instance of map(*)"/>            
+        </x:scenario>
+        <x:scenario label="Non-error case: as-is and flat both appear but flat is not true" catch="no">  
+            <x:context>
+                <catalog>
+                    <merge>
+                        <flat/>
+                        <as-is>1</as-is>
+                    </merge>
+                </catalog>
+            </x:context>
+            <x:call template="detect-multiple-structuring-directives"/>
+            <x:expect label="No XSLT error" select="()"/>
+        </x:scenario>
+    </x:scenario>
+
+    <x:scenario label="Tests for combine-back-matter template">
+        <x:scenario label="Back matter as child of catalog">
+            <x:context>
+                <catalog>
+                    <back-matter>
+                        <resource>
+                            <title>Ref CCC</title>
+                        </resource>
+                        <resource uuid="0050231f-4fd0-43d6-8fa0-431367cd83e2">
+                            <title>Ref BBB</title>
+                        </resource>
+                        <resource opr:id="ref001">
+                            <title>Ref AAA</title>
+                        </resource>
+                    </back-matter>
+                </catalog>
+            </x:context>
+            <x:call template="combine-back-matter"/>
+            <x:expect label="back-matter with items, @opr:id omitted">
+                <back-matter>
+                    <resource>
+                        <title>Ref CCC</title>
+                    </resource>
+                    <resource uuid="0050231f-4fd0-43d6-8fa0-431367cd83e2">
+                        <title>Ref BBB</title>
+                    </resource>
+                    <resource>
+                        <title>Ref AAA</title>
+                    </resource>
+                </back-matter>
+            </x:expect>
+        </x:scenario>
+        <x:scenario label="Back matter as child of selection">
+            <x:context>
+                <catalog>
+                    <selection uuid="xyz-tiny_catalog">
+                        <control id="x1"><title>Control X1</title></control>
+                        <back-matter>
+                            <resource>
+                                <title>Ref CCC</title>
+                            </resource>
+                            <resource uuid="0050231f-4fd0-43d6-8fa0-431367cd83e2">
+                                <title>Ref BBB</title>
+                            </resource>
+                        </back-matter>
+                    </selection>
+                    <selection uuid="xyz-tiny_catalog2">
+                        <control id="x2"><title>Control X2</title></control>
+                        <back-matter>
+                            <resource opr:id="ref001">
+                                <title>Ref AAA</title>
+                            </resource>
+                        </back-matter>
+                    </selection>
+                </catalog>
+            </x:context>
+            <x:call template="combine-back-matter"/>
+            <x:expect label="back-matter with items, @opr:id omitted">
+                <back-matter>
+                    <resource>
+                        <title>Ref CCC</title>
+                    </resource>
+                    <resource uuid="0050231f-4fd0-43d6-8fa0-431367cd83e2">
+                        <title>Ref BBB</title>
+                    </resource>
+                    <resource>
+                        <title>Ref AAA</title>
+                    </resource>
+                </back-matter>
+            </x:expect>
+        </x:scenario>
+        <x:scenario label="Back matter in multiple places with duplication">
+            <x:context>
+                <catalog>
+                    <selection uuid="xyz-tiny_catalog">
+                        <control id="x1"><title>Control X1</title></control>
+                        <back-matter>
+                            <resource>
+                                <title>Ref CCC</title>
+                            </resource>
+                            <resource uuid="0050231f-4fd0-43d6-8fa0-431367cd83e2">
+                                <title>Ref BBB, first</title>
+                            </resource>
+                            <resource opr:id="ref001">
+                                <title>Ref AAA</title>
+                            </resource>
+                        </back-matter>
+                    </selection>
+                    <selection uuid="xyz-tiny_catalog2">
+                        <control id="x2"><title>Control X2</title></control>
+                        <back-matter>
+                            <resource>
+                                <title>Ref CCC</title>
+                            </resource>
+                            <resource uuid="0050231f-4fd0-43d6-8fa0-431367cd83e2">
+                                <title>Ref BBB, second</title>
+                            </resource>
+                            <resource opr:id="ref001">
+                                <title>Ref AAA</title>
+                            </resource>
+                        </back-matter>
+                    </selection>
+                    <back-matter>
+                        <resource>
+                            <title>Ref CCC</title>
+                        </resource>
+                        <resource uuid="0050231f-4fd0-43d6-8fa0-431367cd83e2">
+                            <title>Ref BBB, third</title>
+                        </resource>
+                        <resource opr:id="ref001">
+                            <title>Ref AAA</title>
+                        </resource>
+                    </back-matter>
+                </catalog>
+            </x:context>
+            <x:call template="combine-back-matter"/>
+            <x:expect label="back-matter with last item for each distinct uuid or distinct opr:id.">
+                <back-matter>
+                    <resource>
+                        <title>Ref CCC</title>
+                    </resource>
+                    <resource uuid="0050231f-4fd0-43d6-8fa0-431367cd83e2">
+                        <title>Ref BBB, third</title>
+                    </resource>
+                    <resource>
+                        <title>Ref AAA</title>
+                    </resource>
+                    <resource>
+                        <title>Ref CCC</title>
+                    </resource>
+                    <resource>
+                        <title>Ref CCC</title>
+                    </resource>
+                </back-matter>
+            </x:expect>
+        </x:scenario>
+        <x:scenario label="No back matter in input context">
+            <x:context>
+                <catalog>
+                    <selection>
+                        <back-matter/>
+                    </selection>
+                    <back-matter/>
+                </catalog>
+            </x:context>
+            <x:call template="combine-back-matter"/>
+            <x:expect label="Nothing (in particular, no empty back-matter wrapper)" select="()"/>
+        </x:scenario>
+    </x:scenario>
+
+    <x:scenario label="Tests for match=selection template">
+        <!-- In <x:context>, <selection> must have a parent element.
+            Otherwise, we reach the match="/*" template instead of the
+            match="selection" template. -->
+        <x:scenario label="Parameters grouped and ungrouped">
+            <x:context select="//o:selection">
+                <catalog>
+                    <selection id="xyz-tiny_catalog" opr:id="xyz-tiny_catalog#xyz-tiny_catalog">
+                        <param id="param-a">
+                            <label>Param A</label>
+                            <constraint>no control</constraint>
+                        </param>
+                        <group>
+                            <title>Group X of XYZ</title>
+                            <param id="param-x">
+                                <label>Param X</label>
+                                <constraint>no control</constraint>
+                            </param>
+                            <param id="param-y">
+                                <label>Param Y</label>
+                                <constraint>no control</constraint>
+                            </param>
+                            <group>
+                                <title>Group X2</title>
+                                <param id="param-x2">
+                                    <label>Param X2</label>
+                                    <constraint>no control</constraint>
+                                </param>
+                                <param id="param-y2">
+                                    <label>Param Y2</label>
+                                    <constraint>no control</constraint>
+                                </param>
+                            </group>
+                        </group>
+                    </selection>
+                </catalog>
+            </x:context>
+            <x:expect label="All parameters in document order at all group levels">
+                <param id="param-a">
+                    <label>Param A</label>
+                    <constraint>no control</constraint>
+                </param>
+                <param id="param-x">
+                    <label>Param X</label>
+                    <constraint>no control</constraint>
+                </param>
+                <param id="param-y">
+                    <label>Param Y</label>
+                    <constraint>no control</constraint>
+                </param>
+                <param id="param-x2">
+                    <label>Param X2</label>
+                    <constraint>no control</constraint>
+                </param>
+                <param id="param-y2">
+                    <label>Param Y2</label>
+                    <constraint>no control</constraint>
+                </param>
+            </x:expect>
+        </x:scenario>
+        <x:scenario label="Controls grouped and ungrouped">
+            <x:context select="//o:selection">
+                <catalog>
+                    <selection id="xyz-tiny_catalog" opr:id="xyz-tiny_catalog#xyz-tiny_catalog">
+                        <control id="a"><title>Control A</title></control>
+                        <group>
+                            <title>Group X of XYZ</title>
+                            <control id="x1"><title>Control X1</title></control>
+                            <control id="y1"><title>Control Y1</title></control>
+                            <group>
+                                <title>Group X2</title>
+                                <control id="x2"><title>Control X2</title></control>
+                                <control id="y2"><title>Control Y2</title></control>
+                            </group>
+                        </group>
+                    </selection>
+                </catalog>
+            </x:context>
+            <x:expect label="All controls in document order at all group levels">
+                <control id="a"><title>Control A</title></control>
+                <control id="x1"><title>Control X1</title></control>
+                <control id="y1"><title>Control Y1</title></control>
+                <control id="x2"><title>Control X2</title></control>
+                <control id="y2"><title>Control Y2</title></control>
+            </x:expect>
+        </x:scenario>
+        <x:scenario label="Parameters and controls">
+            <x:context select="//o:selection">
+                <catalog>
+                    <selection id="xyz-tiny_catalog" opr:id="xyz-tiny_catalog#xyz-tiny_catalog">
+                        <param id="param-a">
+                            <label>Param A</label>
+                            <constraint>no control</constraint>
+                        </param>
+                        <control id="a"><title>Control A</title></control>
+                        <group>
+                            <title>Group X of XYZ</title>
+                            <param id="param-x1">
+                                <label>Param X1</label>
+                                <constraint>no control</constraint>
+                            </param>
+                            <control id="x1"><title>Control X1</title></control>
+                        </group>
+                    </selection>
+                </catalog>
+            </x:context>
+            <x:expect label="All parameters followed by all controls">
+                <param id="param-a">...</param>
+                <param id="param-x1">...</param>
+                <control id="a">...</control>
+                <control id="x1">...</control>
+            </x:expect>
+        </x:scenario>
+    </x:scenario>
+
+    <!-- Tests for all mode=o:custom-merge templates are in merge-custom.xspec -->
+    
+    <x:scenario label="Tests for match=selection|selection//group mode=o:select template">
+        <x:variable name="ov:control">
+            <control id="x1" opr:id="xyz-tiny_catalog#x1"><title>Control X1</title></control>            
+        </x:variable>
+        <x:scenario label="Context is selection with child control">
+            <x:variable name="ov:context">
+                <catalog uuid="zzz">
+                    <selection>
+                        <control id="x1" opr:id="xyz-tiny_catalog#x1"><title>Control X1</title></control>
+                    </selection>
+                    <merge>
+                        <custom>
+                            <insert-controls>
+                                <include-all/>
+                            </insert-controls>
+                        </custom>
+                    </merge>
+                </catalog>
+            </x:variable>
+            <x:context mode="o:select" select="$ov:context//o:selection">
+                <x:param name="import-instruction" tunnel="yes" select="$ov:context//o:insert-controls"/>
+            </x:context>
+            <x:expect label="Child control" select="$ov:control"/>
+        </x:scenario>
+        <x:scenario label="Context is selection with child group">
+            <x:variable name="ov:context">
+                <catalog uuid="zzz">
+                    <selection>
+                        <group id="parent">
+                            <control id="x1" opr:id="xyz-tiny_catalog#x1"><title>Control X1</title></control>
+                        </group>
+                    </selection>
+                    <merge>
+                        <custom>
+                            <insert-controls>
+                                <include-all/>
+                            </insert-controls>
+                        </custom>
+                    </merge>
+                </catalog>
+            </x:variable>
+            <x:context mode="o:select" select="$ov:context//o:selection">
+                <x:param name="import-instruction" tunnel="yes" select="$ov:context//o:insert-controls"/>
+            </x:context>
+            <x:expect label="Descendant control" select="$ov:control"/>
+        </x:scenario>
+        <x:scenario label="Context is group with nested group">
+            <x:variable name="ov:context">
+                <catalog uuid="zzz">
+                    <selection>
+                        <group id="parent">
+                            <group id="child">
+                                <control id="x1" opr:id="xyz-tiny_catalog#x1"><title>Control X1</title></control>
+                            </group>
+                        </group>
+                    </selection>
+                    <merge>
+                        <custom>
+                            <insert-controls>
+                                <include-all/>
+                            </insert-controls>
+                        </custom>
+                    </merge>
+                </catalog>
+            </x:variable>
+            <x:context mode="o:select" select="$ov:context//o:group[@id='parent']">
+                <x:param name="import-instruction" tunnel="yes" select="$ov:context//o:insert-controls"/>
+            </x:context>
+            <x:expect label="Descendant control" select="$ov:control"/>
+        </x:scenario>
+        <x:scenario label="Context is group with child control">
+            <x:variable name="ov:context">
+                <catalog uuid="zzz">
+                    <selection>
+                        <group id="parent">
+                            <control id="x1" opr:id="xyz-tiny_catalog#x1"><title>Control X1</title></control>
+                        </group>
+                    </selection>
+                    <merge>
+                        <custom>
+                            <insert-controls>
+                                <include-all/>
+                            </insert-controls>
+                        </custom>
+                    </merge>
+                </catalog>
+            </x:variable>
+            <x:context mode="o:select" select="$ov:context//o:group">
+                <x:param name="import-instruction" tunnel="yes" select="$ov:context//o:insert-controls"/>
+            </x:context>
+            <x:expect label="Child control" select="$ov:control"/>
+        </x:scenario>
+    </x:scenario>
+
+    <!-- Tests for o:merge-groups-as-is template are in merge-as-is.xspec -->
+    <!-- Tests for combine-elements template are in merge-combine.xspec -->
+    <!-- Tests for all mode="o:combine-elements" templates are in merge-combine.xspec -->
+
+    <x:scenario label="Tests for match=@opr:id template">
+        <x:context select="@opr:id">
+            <foo opr:id="intermediate-value-id"/>
+        </x:context>
+        <x:expect label="Nothing" select="()"/>
+    </x:scenario>
 </x:description>