Some of the KDE people (Mark Mutz, Ingo Kloecker) noted:
http://lists.gnupg.org/pipermail/gnupg-users/2001-July/009397.html
that ascii-armor comment lines may contain non-7-bit text.
It is not clear whether this is a "SHOULD warn" situation.
I see no clause defining the charset of text in Armor Headers.
Should an armored block be constrained to use only 7-bit
mail-safe characters, or should it be stated that Armor
Headers may be in UTF-8, or native charset, or what?
Either user-defined text in Armor Headers MAY contain
non-7-bit characters, or SHOULD NOT, or MUST NOT.
If non-7-bit text is allowed, there ought to be a note in
2440/6.2 which warns that the use of an 8-bit charset
will make the 'armored' output non-mail-safe.