When is T designator required with duration?

3.2.6.1 says:

 "The designator 'T' shall be absent if all of the time items are absent"

Shouldn't this be "if and only if" rather than "if"?  I don't think 
something like P24H can be allowed since there would be an ambiguity 
whether M meant months or minutes.  (The use of "shall" here feels rather 
ISO-ish; tt would be more stylistically consistent to use "must".)

James

Received on Sunday, 28 April 2002 08:08:46 UTC