Name,Description,Reference
alg,Explicitly declared signature algorithm,"[RFC 9421, Section 2.3]"
created,Timestamp of signature creation,"[RFC 9421, Section 2.3]"
expires,Timestamp of proposed signature expiration,"[RFC 9421, Section 2.3]"
keyid,Key identifier for the signing and verification keys used to create this signature,"[RFC 9421, Section 2.3]"
nonce,A single-use nonce value,"[RFC 9421, Section 2.3]"
tag,An application-specific tag for a signature,"[RFC 9421, Section 2.3]"