diff --git a/pep-0631.rst b/pep-0631.rst
index d30fe3275..d4a967413 100644
--- a/pep-0631.rst
+++ b/pep-0631.rst
@@ -58,7 +58,9 @@ Every element SHOULD be an `entry <#entries>`_.
     ]
 
 Any element MAY be an inline table to support possible future functionality.
-Backends MUST silently ignore these until the specification is extended.
+Backends MUST error when encountering these until the specification is extended.
+Other parsers SHOULD do the same, though they MAY consider the entire enclosing
+field as `dynamic`_.
 
 optional-dependencies
 ---------------------
@@ -129,6 +131,7 @@ CC0-1.0-Universal license, whichever is more permissive.
 .. _fields defined in PEP 621: https://www.python.org/dev/peps/pep-0621/#dependencies-optional-dependencies
 .. _PEP 508 strings: https://www.python.org/dev/peps/pep-0508/
 .. _Requires-Dist: https://packaging.python.org/specifications/core-metadata/#requires-dist-multiple-use
+.. _dynamic: https://www.python.org/dev/peps/pep-0621/#dynamic
 .. _Provides-Extra: https://packaging.python.org/specifications/core-metadata/#provides-extra-multiple-use
 .. _docker-compose: https://github.com/docker/compose/blob/789bfb0e8b2e61f15f423d371508b698c64b057f/setup.py#L28-L61