Merge pull request pypa#1988 from ncoghlan/clarify-environment-marker-comparisons

Attempt to clarify environment marker evaluation

Author: pradyunsg

source/specifications/core-metadata.rst

@@ -574,14 +574,14 @@ The format of a requirement string contains from one to four parts:
 * An environment marker after a semicolon. This means that the
   requirement is only needed in the specified conditions.
 
-See :pep:`508` for full details of the allowed format.
-
 The project names should correspond to names as found
 on the `Python Package Index`_.
 
 Version specifiers must follow the rules described in
 :doc:`version-specifiers`.
 
+See :ref:`dependency-specifiers` for full details of the allowed format.
+
 Examples::
 
     Requires-Dist: pkginfo
@@ -1071,6 +1071,9 @@ History
 - October 2025: Clarified that ``License-Expression`` applies to the containing
   distribution file and not the project itself.
 
+- January 2026: Replaced outdated direct reference to :pep:`508` with a
+  reference to :ref:`dependency-specifiers`.
+
 ----
 
 .. [1] reStructuredText markup:

source/specifications/dependency-groups.rst

@@ -209,8 +209,8 @@ The output is therefore valid ``requirements.txt`` data.
         realized_group = []
         for item in raw_group:
             if isinstance(item, str):
-                # packaging.requirements.Requirement parsing ensures that this is a valid
-                # PEP 508 Dependency Specifier
+                # packaging.requirements.Requirement parsing ensures that this
+                # is a valid dependency specifier
                 # raises InvalidRequirement on failure
                 Requirement(item)
                 realized_group.append(item)