Support timestamp in ISO 8601

[Stuv7CB]

Hello. ISO 8601 is recommended international format for time representation, would it be possible to add support of such format into specifications

The following profile of ISO 8601 [ISO8601] dates SHOULD be used in new protocols on the Internet. This is specified using the syntax description notation defined in [ABNF].

[mrossinek]

This seems like a sensible suggestion 👍 And it should be fairly trivial to distinguish from the more human-readable format currently required by the spec so we can probably support both at the same time.