[Imap-protocol] Parsing resp-text

[Peter Bowen]

I'm working on some IMAP client code, and hit the following portion of
ABNF grammer in RFC 3501:

resp-text = ["[" resp-text-code "]" SP] text

Should the following lines be considered protocol errors?

* NO [UNSEEN]
* NO [TRYCREATE
* NO [FOO(BAR)]

The resp-text rule says "[" must have a matching "]" and the
resp-text-code rule says UNSEEN must be followed by a nz-number and
the the first word after the [ must be an atom, so they would appear
to be errors.

However, the first part of resp-text is optional, so should these just
be considered to have text ("[UNSEEN]", "[TRYCREATE", and "[FOO(BAR)]"
and no response code?

Thanks.
Peter