MDX format date expression

Hi, could someone please assist a MDX novice with formatting the column values to "yyyy-MM" for the following MDX that runs and returns the Month Start Date as datetime i.e. 2008-01-01 00:00:00.000Thanks in advanceStuartSELECT{[Carrier Local Date].[Month Start Date].[Month Start Date]}ON COLUMNS,{ ORDER( { [Measures].[New Users] }, ( [Measures].[# Processed Messages] ), BDESC ) }ON ROWSFROM [ReportingCube]