The generic string special (GSS) table is used to determine if a character is valid in a picture string and, if so, what offset into the generic string character (GSC) table describes its subset. The mask value from the GSC table is used to determine which characters satisfy the subset. Each character in the text being scanned is represented in the generic string master (GSM) table by a hexadecimal code that indicates which subsets that character belongs to (see Creating ISPF terminal translation tables). The hexadecimal code in the GSM is ANDed with the mask value from the GSC. Any nonzero result is considered a match.

In Table 1, a # (‘7B’) has a value in the GSS of ‘07’. At offset ‘07’ in the GSC (actually the eighth entry in the GSC, the first being offset ‘00’), the mask value is a X'40'. This means any character that is a member of the numeric subset, when ANDed with a X'40', will produce a nonzero result.