diff --git a/share/include/mfs_library/make_makefile.bash b/share/include/mfs_library/make_makefile.bash
index d741df5..cabfd0f 100644
--- a/share/include/mfs_library/make_makefile.bash
+++ b/share/include/mfs_library/make_makefile.bash
@@ -323,7 +323,7 @@ function show_arg_list_status()
 # \returns void
 #
 # \details
-#   Output a makefile target recepie for the given input parameters.
+#   Output a makefile target recipe for the given input parameters.
 #
 # \private
 ###############################################################################/
@@ -396,11 +396,11 @@ function add_target()
 
   print_m -j
 
-  # include openscad generated depend file (use if it exsists "-")
+  # include openscad generated depend file (use if it exists "-")
   print_m -j
   print_m -j -include $filename_depend
 
-  # add target file directory dependancy
+  # add target file directory dependency
   print_m -j
   print_m -j $filename_out : \| $(file_utility --pathname $filename_out)
 
@@ -574,7 +574,7 @@ function generate_targets()
       generate_targets \
         --out_stem "$out_stem$i" \
         --tuple_list "$tuple_list [$i]" \
-        --opts_scad "$opts_scad $this_opt_val" \
+        --opts_scad "$opts_scad -D __mfs_$i=true $this_opt_val" \
         --opts_sets "$remain_opt_sets"
     done
   fi
diff --git a/share/include/pmf/df1/base_system b/share/include/pmf/df1/base_system
index 3311a32..52672c8 100644
--- a/share/include/pmf/df1/base_system
+++ b/share/include/pmf/df1/base_system
@@ -41,24 +41,24 @@ time      := $(word 2,$(strip $(subst -,$(space),$(datetime))))
 # Commands
 #------------------------------------------------------------------------------#
 
-path_mkdir  := $(call first_of,mkdir)
-path_rmdir  := $(call first_of,rmdir)
-path_rm     := $(call first_of,rm)
-path_cp     := $(call first_of,cp)
-path_tar    := $(call first_of,tar)
-path_zip    := $(call first_of,zip)
-path_tput   := $(call first_of,tput)
-path_seq    := $(call first_of,seq)
-path_test   := $(call first_of,test)
-path_sort   := $(call first_of,sort)
-path_grep   := $(call first_of,grep)
-path_cat    := $(call first_of,cat)
-path_sed    := $(call first_of,sed)
-path_head   := $(call first_of,head)
-path_tail   := $(call first_of,tail)
-path_touch  := $(call first_of,touch)
-path_chmod  := $(call first_of,chmod)
-path_ls     := $(call first_of,ls)
+path_mkdir  := $(call first_of,$(path_mkdir) mkdir)
+path_rmdir  := $(call first_of,$(path_rmdir) rmdir)
+path_rm     := $(call first_of,$(path_rm) rm)
+path_cp     := $(call first_of,$(path_cp) cp)
+path_tar    := $(call first_of,$(path_tar) tar)
+path_zip    := $(call first_of,$(path_zip) zip)
+path_tput   := $(call first_of,$(path_tput) tput)
+path_seq    := $(call first_of,$(path_seq) seq)
+path_test   := $(call first_of,$(path_test) test)
+path_sort   := $(call first_of,$(path_sort) sort)
+path_grep   := $(call first_of,$(path_grep) grep)
+path_cat    := $(call first_of,$(path_cat) cat)
+path_sed    := $(call first_of,$(path_sed) sed)
+path_head   := $(call first_of,$(path_head) head)
+path_tail   := $(call first_of,$(path_tail) tail)
+path_touch  := $(call first_of,$(path_touch) touch)
+path_chmod  := $(call first_of,$(path_chmod) chmod)
+path_ls     := $(call first_of,$(path_ls) ls)
 
 #------------------------------------------------------------------------------#
 # OS Configuration
diff --git a/share/include/pmf/df1/doxygen_rules b/share/include/pmf/df1/doxygen_rules
index 559848e..c5263d2 100644
--- a/share/include/pmf/df1/doxygen_rules
+++ b/share/include/pmf/df1/doxygen_rules
@@ -105,10 +105,10 @@ install-doxygen: install-doxygen-html
 uninstall-doxygen: uninstall-doxygen-html
 
 # install ordering
-install-doxygen-html: install-doxygen-html-files install-doxygen-update-html-index
+install-doxygen-html: install-doxygen-html-files install-doxygen-tag install-doxygen-update-html-index
 	$(call target_end)
 
-# copy files
+# copy html files
 install-doxygen-html-files: $(doxygen_stamp) | $(install_prefix_html) $(install_prefix_html)$(docs_install_id)
 	$(call target_begin)
 	( \
@@ -116,6 +116,11 @@ install-doxygen-html-files: $(doxygen_stamp) | $(install_prefix_html) $(install_
 		$(cp_a) $(html_output) $(install_prefix_html)$(docs_install_id) \
 	)
 
+# copy doxygen tag file
+install-doxygen-tag: $(doxygen_stamp) | $(install_prefix_html) $(install_prefix_html)$(docs_install_id)
+	$(call target_begin)
+	$(cp_a) $(doxygen_tag) $(install_prefix_html)$(docs_install_id)$(dir_level_sep)$(notdir $(doxygen_tag))
+
 # create toc entry and update index
 install-doxygen-update-html-index: | $(install_prefix_html)$(docs_install_id)
 	$(call target_begin)
@@ -130,7 +135,7 @@ $(install_prefix_html)$(docs_install_id): ; $(mkdir_p) $@
 uninstall-doxygen-html: uninstall-doxygen-html-files doxygen-update-html-index
 	$(call target_end)
 
-# remove files
+# remove html files
 uninstall-doxygen-html-files:
 	$(call target_begin)
 	-( \
@@ -156,7 +161,7 @@ uninstall-doxygen: uninstall-doxygen-pdf
 install-doxygen-pdf: install-doxygen-pdf-files install-doxygen-update-pdf-index
 	$(call target_end)
 
-# copy files
+# copy pdf files
 install-doxygen-pdf-files: $(latex_stamp) | $(install_prefix_pdf) $(install_prefix_pdf)$(docs_install_id)
 	$(call target_begin)
 	( \
@@ -180,7 +185,7 @@ $(install_prefix_pdf)$(docs_install_id): ; $(mkdir_p) $@
 uninstall-doxygen-pdf: uninstall-doxygen-pdf-files doxygen-update-pdf-index
 	$(call target_end)
 
-# remove files
+# remove pdf files
 uninstall-doxygen-pdf-files:
 	$(call target_begin)
 	-( \
diff --git a/share/include/pmf/df1/doxygen_system b/share/include/pmf/df1/doxygen_system
index 37cef3f..91d4838 100644
--- a/share/include/pmf/df1/doxygen_system
+++ b/share/include/pmf/df1/doxygen_system
@@ -30,9 +30,10 @@
 # Commands
 #------------------------------------------------------------------------------#
 
-path_doxygen := $(call first_of,doxygen)
+path_doxygen := $(call first_of,$(path_doxygen) doxygen)
 path_openscad_dif := \
   $(call first_of, \
+    $(path_openscad_dif) \
     $(AMU_TOOL_PREFIX)openscad-dif-$(AMU_TOOL_VERSION) \
     $(AMU_TOOL_PREFIX)openscad-dif \
   )
diff --git a/share/include/pmf/df1/scopes_system b/share/include/pmf/df1/scopes_system
index 92e427e..b822dca 100644
--- a/share/include/pmf/df1/scopes_system
+++ b/share/include/pmf/df1/scopes_system
@@ -30,14 +30,15 @@
 # Commands
 #------------------------------------------------------------------------------#
 
-path_openscad := $(call first_of,openscad openscad-nightly)
+path_openscad := $(call first_of,$(path_openscad) openscad openscad-nightly)
 path_openscad_seam := \
   $(call first_of, \
+    $(path_openscad_seam) \
     $(AMU_TOOL_PREFIX)openscad-seam-$(AMU_TOOL_VERSION) \
     $(AMU_TOOL_PREFIX)openscad-seam \
   )
-path_bash := $(call first_of,bash)
-path_gnumake := $(call first_of,gnumake gmake make)
+path_bash := $(call first_of,$(path_bash) bash)
+path_gnumake := $(call first_of,$(path_gnumake) gnumake gmake make)
 
 #------------------------------------------------------------------------------#
 # OS Configuration
diff --git a/src/openscad_dif.dox b/src/openscad_dif.dox
index 8c8bd9b..af06f56 100644
--- a/src/openscad_dif.dox
+++ b/src/openscad_dif.dox
@@ -38,7 +38,7 @@
    "+"+"/"    | end nested comment block.
 
   As identified in the above table, the filter supports nested
-  comments, which are useful for documenting the bahavior of include
+  comments, which are useful for documenting the behavior of include
   files and macros. A single level of nesting is permitted and must
   exists within a normal comment block. The content of nested comment
   blocks is discarded by the filter. See the flex documentation for
@@ -157,12 +157,13 @@
    OPENSCAD_EXT       | openscad script extension
 
 
-  \subsection openscad_dif_sm_adc Doxygen Function Summary
+  \subsection openscad_dif_sm_adc Doxygen Input Filter Functions Summary
 
-  In addition to the normal Doxygen [special commands], here is a list
-  of additional filter-provided command functions that can be used for
-  document markup. The documentation for these functions may be found
-  in section the \ref openscad_dif_sm_afc "filter commands".
+  In addition to the standard Doxygen [special commands], here is a
+  list of additional commands provided by the input filter that can be
+  used within documentation. The description for these functions can be
+  found in the section \ref openscad_dif_sm_afc "filter commands"
+  below.
 
   | internal commands               | description
   |:--------------------------------|:------------------------------------
diff --git a/src/openscad_seam.dox b/src/openscad_seam.dox
index bce680c..cce5047 100644
--- a/src/openscad_seam.dox
+++ b/src/openscad_seam.dox
@@ -16,10 +16,27 @@
 
   OpenSCAD script extractor and auto-make tool (seam).
 
-  Extract makefile-generation- and OpenSCAD-build-scripts embedded into
-  comment blocks, of an OpenSCAD input file. These scripts may be used
-  to generate makefiles that automate the compilation of OpenSCAD
-  design targets.
+  This program extracts embedded scripts, makefile generation scripts
+  and OpenSCAD build scripts, from comment blocks, from ab OpenSCAD
+  source file. These scripts may be used to generate makefiles that
+  automate the compilation of OpenSCAD design targets.
+
+  \subsubsection openscad_seam_sm_av Automatic Variables
+
+  The following tables list variables predefined that may be used by
+  the extracted makefile scripts.
+
+  <b>Input File:</b>
+
+   name                   | description
+  :-----------------------|:----------------------------------------------
+   \__SOURCE_FILE\__      | input source file name
+   \__SCOPE_FILE\__       | file name assigned to the extracted script
+   \__MAKE_FILE\__        | file name assigned to the generated makefile
+   \__LIB_PATH\__         | makefile script library path
+   \__PREFIX\__           | makefile target output path prefix
+   \__AMU_INCLUDE_PATH\__ | path for optional makefile includes
+   sc_openscad            | path to the OpenSCAD installation to use
 
 *******************************************************************************/