# 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'
```