It shouldn't be up to the implementation to decide (IMHO). If the goal
of the WG is "to provide IETF standards for the algorithms and formats
of PGP processed objects", then surely some standard file formats
should be defined [*] : e.g. keyring, encrypted file, signed file,
etc.
... even if that just means documenting what GPG does now (and what
PGP2,etc) did as de-facto standards....
Rachel