fix(AIP-192): expand xref resolution rules (#1437)

aip/general/0192.md

@@ -92,9 +92,21 @@ documentation page containing the diagram as an image.
 
 ### Cross-references
 
-Comments **may** "link" to another component (service, method, message, field,
-enum, or enum value) by using the fully-qualified name of the element as a
-Markdown reference link. For example: `[Book][google.example.v1.Book]`
+A comment can "link" to another component (service, method, message, field,
+enum, or enum value) as a Markdown reference link. The reference **must** be one
+of the following forms:
+- The fully-qualified name of the element e.g. `[Book][google.example.v1.Book]`
+- A scope-relative reference qualified e.g. `[Sci-Fi genre][Genre.GENRE_SCI_FI]`
+- An implied reference e.g. `[Book][]` which equates to `[Book][Book]`
+
+These references are solved as per [name resolution][] rules.
+
+Containing fields names **must not** be used in references. They will not
+resolve. The original definition **must** be referenced instead. For example,
+`[author][Book.author.family_name]` where `author` is a field of `Book`, will
+not resolve, but `[author][Author.family_name]` would.
+
+[name resolution]: https://protobuf.dev/programming-guides/proto3/#name-resolution
 
 ### External links
 
@@ -144,6 +156,7 @@ of inadvertent omissions of the internal content annotation.
 
 ## Changelog
 
+- **2024-10-29**: Include cross-reference resolution rules.
 - **2023-08-11**: Expand deprecated comment requirement to all components.
 - **2021-04-20**: Added guidance for deprecated services and RPCs.
 - **2020-04-01**: Added guidance requiring absolute URLs for external links.