applied more suggestions from review

aep/general/0137/aep.md.j2

@@ -4,7 +4,7 @@ In REST APIs, it is customary to make a `PUT` request to a collection's URI (for
 example, `/v1/publishers/{publisher}/books`) in order to create or replace a new
 resource within that collection.
 
-Resource-oriented design (AEP-121) honors this pattern through the `Apply`
+[Resource-oriented design](/resources) honors this pattern through the `Apply`
 method. These RPCs accept the parent collection and the resource to create or
 replace, and then return, the final resource.
 
@@ -28,7 +28,7 @@ Apply methods are specified using the following pattern:
   **should** be the only variable in the URI path.
   - The collection identifier (`books` in the above example) **must** be a
     literal string.
-- The operation **must** have [strong consistency][].
+- The operation **must** have [strong consistency](/resources#strong-consistency).
 
 {% tab proto %}
 
@@ -71,12 +71,9 @@ Apply methods implement a common request message pattern:
 {% sample '../example.proto', 'message ApplyBookRequest' %}
 
 - A `path` field specifying the path of the resource **must** be included.
-  - The field **must** be [annotated as `REQUIRED`][aep-203].
-  - The field **must** identify the [resource type][aep-4] of the resource
+  - The field **must** be [annotated as `REQUIRED`](/field-behavior-documentation).
+  - The field **must** identify the [resource type](/resource-types) of the resource
     being applied.
-- The request message **must not** contain any other required fields and
-  **should not** contain other optional fields except those described in this
-  or another AEP.
 
 {% tab oas %}
 
@@ -92,7 +89,7 @@ Apply methods implement a common request message pattern:
   schema.
   - The response **should** include the fully-populated resource, and **must**
     include any fields that were provided unless they are input only (see
-    AEP-203).
+    [field behavior](/field-behavior-documentation)).
 
 {% tab proto %}
 
@@ -106,8 +103,8 @@ Apply methods implement a common request message pattern:
 
 ### Errors
 
-See [errors][], in particular [when to use PERMISSION_DENIED and NOT_FOUND
-errors][permission-denied].
+See [errors](/errors), in particular [when to use PERMISSION_DENIED and NOT_FOUND
+errors](/errors#permission-denied).
 
 ## Interface Definitions
 
@@ -127,18 +124,7 @@ errors][permission-denied].
 
 ## Further reading
 
-- For ensuring idempotency in `Apply` methods, see AEP-155.
-- For naming resources involving Unicode, see AEP-210.
-
-[aep-121]: ./0121.md
-[aep-122]: ./0122.md
-[aep-4]: ./0004.md
-[aep-155]: ./0155.md
-[aep-203]: ./0203.md
-[aep-210]: ./0210.md
-[data plane]: ./0111.md#data-plane
-[errors]: ./0193.md
-[field_behavior]: ./203.md
-[Declarative clients]: ./0003.md#declarative-clients
-[permission-denied]: ./0193.md#permission-denied
+- For ensuring idempotency in `Apply` methods, see [idempotency](/idempotency).
+- For naming resources involving Unicode, see [unicode](/unicode).
+
 [strong consistency]: ./0121.md#strong-consistency