What, if any, are the IETF namespace notations for OpenPGP signatures?

cn flag

RFC 4880 section, "Notation Data," describes how arbitrary additional notations in the form of name-value pairs can be included in an OpenPGP signature packet. Regarding names, it says the following:

Notation names are arbitrary strings encoded in UTF-8. They reside in two namespaces: The IETF namespace and the user namespace.

The IETF namespace is registered with IANA. These names MUST NOT contain the "@" character (0x40). This is a tag for the user namespace.

The document does not give any indication of where this registry might be accessible, and I was unable to find any documentation of existing notation data names in the IETF namespace (or, indeed, any significant use of the notation data field at all). Do such notations actually exist, and if so where are they documented?

dave_thompson_085 avatar
cn flag
All IANA registries for standard protocols are at ; this one is at and is indeed currently empty
cn flag
Thank you for the link, @dave_thompson_085 ; if you post that as an answer I will accept it.

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