Indicates the number of instances of the outermost column group that appear outside the row headers.
|Data type and length||Integer|
|Cardinality||0-1: Optional element that can occur once or not at all|
The minimum value for the GroupsBeforeRowHeaders element is 0. The maximum value is 2147573647.
A subtotal column in a matrix is considered a part of the last detail column; that is, the rightmost detail column in a matrix that reads left-to-right, and the leftmost detail column in a matrix that reads right-to-left. The subtotal column moves with that column.