Other -15 comments

[David Shaw <[e-mail]>]

I recently did a read-over of -15.  I've already sent the minor text
nits in other mail.  These are comments that rise (marginally) above
simple wording questions.  Much apologies for the late submission.

*****

5.5.2. Public Key Packet Formats says "Third, there are minor
weaknesses in the MD5 hash algorithm that make developers prefer other
algorithms."  Suggest dropping the word "minor".

*****

Section 5.5.2. Public Key Packet Formats says:

  V3 keys are deprecated; an implementation SHOULD NOT generate a V3
  key, but MAY accept it.

but section 11.1. Key Structures says:

  V3 keys are deprecated. Implementations MUST NOT generate new V3
  keys, but MAY continue to use existing ones.

These can't both be correct.  I lean towards MUST NOT here,
personally.

*****

The first two paragraphs in section 6.4. Decoding Radix-64 contradict
each other.  The first says that all non-radix-64 characters must be
ignored.  The second says that non-radix-64 characters probably
indicate a transmission error, "about which a warning message or even
a message rejection might be appropriate under some circumstances".

Suggest going with the second.

*****

David