The IF_NULL command is a hybrid version of the normal IF command. It allows one or more field(s) to be tested for the "null" values.
For a definition of the *NULL value for each of the field types, refer to 7.12.1 CHANGE Parameters.
Also See
7.73.2 IF_NULL Comments / Warnings
Required
IF_NULL ------ FIELD ------------ field name -----------------|
| expandable group expression |
| |
--------- 100 max ----------