comment on valueType vs xs:type in A.2

My apologies for the tardiness of this comment.  This comment is on Section
A.2 of WSS-SOAPMessageSecurity.

I suggest that the valueType attribute be deleted.  The use of xs:dateTime
should be required, not recommended.  I also suggest removing the phrases
"for interoperability" and "for increased interoperability" as these don't
add significantly to the understanding or the requirements.

My suggested text:

It is REQUIRED that all time references use this type.  It is further
RECOMMENDED that all references be in UTC Time.

Rationale:
While it is theoretically possible for other dateTime formats, say unix
time, to be used, in practice all indications are that xml schema date time
will be the standard.  There does not appear to be any significant demand
for this flexible functionality.  Interoperability is considerabily helped
by changing a Recommended to a Required, as then the fallback case and the
use (or even prohibition) of valueType does not have to be defined through
other means, such as profiles or interop comments. Also, using Schema's type
attribute instead of a wss specific valueType means that schema validators
can be used to validate the format of the dateTime, something which is not
possible today with the use of the valueType.

Cheers,
Dave Orchard