You can do a lookup on this within the SQL Server BOL "MDSCHEMA_MEASURES Rowset" - http://msdn.microsoft.com/en-us/library/ms126250.aspx
An enumeration that identifies how a measure was derived. Can be one of the following values:
MDMEASURE_AGGR_SUM (1)
MDMEASURE_AGGR_COUNT (2)
MDMEASURE_AGGR_MIN (3)
MDMEASURE_AGGR_MAX (4)
MDMEASURE_AGGR_AVG (5)
MDMEASURE_AGGR_VAR (6)
MDMEASURE_AGGR_STD (7) identifies that the measure was derived from an aggregation function that was SUM, COUNT, MIN, MAX, AVG, VAR, or STDEV, respectively.
MDMEASURE_AGGR_CALCULATED (127) identifies that the measure was derived from a formula that was not any single function above.
MDMEASURE_AGGR_UNKNOWN (0) identifies that the measure was derived from an unknown aggregation function or formula.