Displaying Null-Capable Fields
You can use the EVAL debug command to display the null indicator of a null-capable field. The null indicator is an internal variable (similar to the index variable for multiple-occurrence DS) which is named _QRNU_NULL_fieldname. The fieldname can be the name of an array if the array is null-capable.
EVAL _QRNU_NULL_FLD1 Result: _QRNU_NULL_FLD1 = '1'
EVAL FLD1 Result: FLD1 = 'abcde'
If a data structure has null-capable subfields, the null indicators for all the null-capable subfields of the data structure are themselves stored as subfields of the data structure _QRNU_NULL_dsname.
If the data structure is not qualified, the null indicator data structure is not qualified. The names of the null capable subfields are in the form _QRNU_NULL_subfieldname.
EVAL _QRNU_NULL_DS1 Result: _QRNU_NULL_FLD1 OF _QRNU_NULL_DS1 = '1' _QRNU_NULL_FLD1 OF _QRNU_NULL_DS1 = '0'
If the data structure is qualified, the null indicator data structure is qualified. The names of the null capable subfields are the same as the names of the data structure subfields.
EVAL _QRNU_NULL_DS2 Result: _QRNU_NULL_DS2.F1 = '0' _QRNU_NULL_DS2.F2 = '1'
EVAL FLD1 Result: 'abc' EVAL _QRNU_NULL_FLD1 Result: '0' EVAL SUBF2 Result: 0 EVAL _QRNU_NULL_SUBF2 Result: '1' EVAL ARR(3) Result: 13 EVAL _QRNU_NULL_ARR(3) Result: '1' EVAL DS3.INFO(2).SUB4 Result: 'xyz' EVAL _QRNU_NULL_DS3.INFO(2).SUB4 Result: '0'