Key,Summary,Reference
Version,Implementation information,"[RFC9580, Section 6.2.2.1]"
Comment,Arbitrary text,"[RFC9580, Section 6.2.2.2]"
Hash,Hash algorithms used in some v4 cleartext signed messages,"[RFC9580, Section 6.2.2.3]"
Charset,Character set,"[RFC9580, Section 6.2.2.4]"