Interpreting Data-type month-year

Imported from previous forum

[ original email was from Pritam Kamat - pritam.kamat@trialius.com ]
Hello

The description in the Common FIX Syntax Rules for datatype month-year is that it is a "String field representing month of a year. An optional day of the month can be appended or an optional week code".

So formats of
YYYYMM
YYYYMMDD
YYYYMMWW
where
YYYY = 0000-9999
MM = 01-12
DD = 01-31
WW = w1, w2, w3, w4, w5

My question is this: Is there any ambiguity in this or, if assuming a Gregorian Calendar, that it is accepted that:
200402w5 is Fri Feb 27 2004

Also two parties use the month-year field but one uses the YYYYMM form and one uses YYYYMMDD, do they both have to agree to use the same form, or are they considered equal if the YYYYMM part is the same.

Many thanks

Regards
Pritam