But note that the RFC also says that the preferred solution to the problem that X-fields are intended to solve is an easily accessible name registry and a simple registration procedure. If Martin's "be prepared for a ten-year period to acceptance" is serious, what should be done about such a registry?
I'm happy for PyPI to host such a registry. A specificaion for the registry should be part of the PEP for the 1.3 format, but I would propose this structure (without having researched in detail what other registries feature, but with a rough idea what IANA registries typically include): - name of metadata field - name of registrant (individual or PyPI package) - contact email address (published) - expiration date; by default, extensions expire 1 month after their registration, unless renewed; maximum expiration time is 5 years - English description of the field - regular expression to validate the field Deleting undesired extensions would not be possible, instead, one would have to create another extension if the syntax or semantics changes Regards, Martin