Python PEP Caution

I didn't realize until today that Python PEP documents are not static. For example, look at PEP 366. This PEP document was modified many times, from May 1 2007 when it was first created until February 1 2025 when it was last changed. It began as a txt document with history from May 1 2007 to September 16 2022, then was changed to an rst document with history from September 10 2023 to February 1 2025.

Why is this an issue?

Because, when you read a post that references a PEP, unless they provide a copy of the PEP they were referring to, or the commit of the version they are referring to, you can't be certain what they were reading.

While most of the changes don't change the essence of the PEP, some do. You can't know without investigating them all. In the case of PEP 366, substantial changes were made until February 2 2009, after which changes were mostly changes to metadata, formatting and links to referenced resources.

To make matters worse, substantial changes are made even after the status of a PEP has been updated to Finished or Final.

Compare this to the IETF management of RFCs. RFCs are published and don't change substantially. Only metadata is changed to indicate if there are errata or when the RFC is superseded. Corrections are published in separate errata documents. More substantial changes are published in new RFCs that clarify or supersede the original RFC but don't change the RFC.