From FIXwiki

FIX Data Type MonthYear

Name	BaseType	First introduced	Deprecated
MonthYear	String	FIX.4.1

string field representing month of a year. An optional day of the month can be appended or an optional week code.

Valid formats:

YYYYMM

YYYYMMDD

YYYYMMWW

Valid values:

YYYY = 0000-9999; MM = 01-12; DD = 01-31; WW = w1, w2, w3, w4, w5.

Notes

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