Specifies that it is possible for a line item field to be a sub-header. This is useful when drawing line item fields in Invoice Verify. If you draw a field in Invoice Verify, and the field is on a row by itself, and PossibleSubheader is set to 1, the program tries to interpret the row as a sub-header.
0 – disabled (default)
1 – enabled
Optimizing complex line item tables (DOCUMENTS Help topic)