Werner Koch <wk(_at_)gnupg(_dot_)org>:
* I don't think the note
* (Added:) PGP 2.6.X and 5.0 do not trim trailing whitespace from a
"canonical text" signature. They only remove it from cleartext
signatures.
is particularly clear on how to interoperate.
[IMHO, this is not the goal of the RFC]
If the RFC does not demand or recommend that implementations accept
such non-standard signatures created by PGP, then that paragraph
should not be in the main text (it can be put in an appendix).
(Also the wording is bad, trailing whitespace is ignored but not
removed when PGP computes cleartext signatures.)