If match_type is 1, MATCH finds the largest value that is less than or equal to lookup_value. Lookup_array must be ascending.
If match_type is 0, MATCH finds the first value that is exactly equal to lookup_value. Lookup_array can be in any order.
If match_type is -1, MATCH finds the smallest value that is greater than or equal to lookup_value. Lookup_array must be descending.
If match_type is omitted, it is assumed to be 1.
Referenced from Excel Help