PEP 808: include METADATA bump

Signed-off-by: Henry Schreiner <henryfs@princeton.edu>

Author: henryiii

peps/pep-0808.rst

@@ -1,5 +1,5 @@
 PEP: 808
-Title: Including static values in dynamic project metadata
+Title: Including static values in dynamic metadata
 Author: Henry Schreiner <henryschreineriii@gmail.com>,
         Cristian Le <python@lecris.dev>
 Sponsor: Filipe Laíns <lains@python.org>
@@ -19,7 +19,8 @@ Abstract
 This PEP relaxes the constraint on dynamic metadata listed in the ``[project]``
 section in ``pyproject.toml``. It is now permitted to define a static portion
 of a dynamic metadata field in the ``[project]`` table as long as the field is
-a table or array.
+a table or array. Likewise, METADATA 2.6 allows mixed static and dynamic
+metadata to be specified in source distribution metadata.
 
 This allows users to opt into allowing a backend to extend metadata while still
 keeping the static portions of the metadata defined in the standard location in
@@ -254,6 +255,29 @@ and backends can continue to fill it as they choose. However, a backend MUST
 ensure that both the SDist and the wheel metadata include the static metadata
 portion of the project table.
 
+In METADATA 2.2 to 2.5, there are no constraints on entries listed as
+``Dynamic`` (which means a wheel can have different metadata than the SDist for
+that field. Now, metadata fields specified in the SDist are guaranteed to also
+be in the wheel, even if Dynamic is present. The METADATA version will be
+incremented to 2.6. Given this example::
+
+    Dynamic: Requires-Dist
+    Requires-Dist: packaging
+
+Before METADATA 2.6, there are no constraints on a field if it appeared in
+``Dynamic``, so the wheel could contain anything; now in 2.6, any values here
+are guaranteed to be also present in wheels, so the wheel will contain
+``Requires-Dist: packaging``; it may contain more ``Requires-Dist``, but it
+will contain at least that one.
+
+This new point will be added to the guidelines:
+
+* If a multiple use field is present in a source distribution and also marked
+  ``Dynamic``, a wheel can add values, but it must include the one(s) present
+  in the SDist. ``Keywords``, ``Author-Email``, and ``Maintainer-Email`` are
+  comma-separated lists, and can likewise be extended if present.
+
+
 Reference Implementation
 ========================
 
@@ -273,9 +297,6 @@ metadata.
 Backwards Compatibility
 =======================
 
-Using metadata from SDists or wheels is unaffected. The METADATA version does
-not need to be incremented.
-
 This does not affect any existing ``pyproject.toml`` files, since this was
 strictly not allowed before this PEP.