PEP 12 & 1: Add a Change History section

.github/PULL_REQUEST_TEMPLATE/Add a new PEP.md

@@ -37,6 +37,9 @@ If your PEP is not Standards Track, remove the corresponding section.
     * [ ] Reference Implementation
     * [ ] Rejected Ideas
     * [ ] Open Issues
+    * [ ] Acknowledgements
+    * [ ] Footnotes
+    * [ ] Change History
 * [ ] ``Python-Version`` set to valid (pre-beta) future Python version, if relevant
 * [ ] Any project stated in the PEP as supporting/endorsing/benefiting from the PEP formally confirmed such
 * [ ] Right before or after initial merging, [PEP discussion thread](https://peps.python.org/pep-0001/#discussing-a-pep) created and linked to in ``Discussions-To`` and ``Post-History``

peps/pep-0001.rst

@@ -581,7 +581,15 @@ Each PEP should have the following parts/sections:
 13. Footnotes -- A collection of footnotes cited in the PEP, and
     a place to list non-inline hyperlink targets.
 
-14. Copyright/license -- Each new PEP must be placed under a dual license of
+14. Change History -- A summary of major changes the PEP has undergone, based on discussions and feedback.
+    Think of this as a "changelog" or "release notes" for the PEP.  In general, whenever you update the
+    ``Post-History`` header for major changes, add a new bullet item in newest-first (i.e. reverse
+    chronological) order, using the same ``MMM-DD-YYYY`` format, with sub-bullets summarizing the changes.
+    You can consider linking this to the same link as the ``Post-History`` link.  This isn't mandatory, so
+    it's left to the PEP author's discretion, but such a section can be helpful for those following along to
+    understand the evolution of your PEP.  Here is :pep:`an example <694#change-history>`.
+
+15. Copyright/license -- Each new PEP must be placed under a dual license of
     public domain and CC0-1.0-Universal_ (see this PEP for an example).
 
 
@@ -876,6 +884,14 @@ Footnotes
 .. _Contributing Guide: https://github.com/python/peps/blob/main/CONTRIBUTING.rst
 
 
+Change History
+==============
+
+* 2026-02-02
+
+  * Added an optional ``Change History`` section for PEPs, for summarizing changes when updating the
+    ``Post-History`` header.
+
 Copyright
 =========
 

peps/pep-0012.rst

@@ -100,8 +100,8 @@ directions below.
   feature is described in a Final PEP.
 
 - Change the Created header to today's date.  Be sure to follow the
-  format carefully: it must be in ``dd-mmm-yyyy`` format, where the
-  ``mmm`` is the 3 English letter month abbreviation, i.e. one of Jan,
+  format carefully: it must be in ``DD-MMM-YYYY`` format, where the
+  ``MMM`` is the 3 English letter month abbreviation, i.e. one of Jan,
   Feb, Mar, Apr, May, Jun, Jul, Aug, Sep, Oct, Nov, Dec.
 
 - For Standards Track PEPs, after the Created header, add a
@@ -122,7 +122,7 @@ directions below.
 - Post-History can be 'Pending' for now; you'll add dates and corresponding links
   to this header each time you post your PEP to the designated discussion forum
   (and update the Discussions-To header with said link, as above).
-  For each thread, use the date (in the ``dd-mmm-yyy`` format) as the
+  For each thread, use the date (in the ``DD-MMM-YYYY`` format) as the
   linked text, and insert the URLs inline as anonymous reST `hyperlinks`_,
   with commas in between each posting.
 

peps/pep-0012/pep-NNNN.rst

@@ -88,6 +88,15 @@ Footnotes
 [A collection of footnotes cited in the PEP, and a place to list non-inline hyperlink targets.]
 
 
+Change History
+==============
+
+[A summary of major changes the PEP has undergone.  Whenever you update the ``Post-History``, add a new bullet
+item in newest-first (i.e. reverse chronological) order, using the same ``MMM-DD-YYYY`` format, with
+sub-bullets summarizing the changes.  You can use the same link for the date bullet as you do in the
+``Post-History`` addition.]
+
+
 Copyright
 =========