NULL command code

The null command code (-) enables you to reserve one or more positions in a SSA in which a program can store command codes, if they are needed during program execution.

For example, reserve position for two command codes as follows:

GU     PATIENTb*--(PATNObbb=b07755)
       ILLNESSbILLDATEb=19930303)
       TREATMNT

Using the null command code lets you use the same set of SSAs for more than one purpose. However, dynamically modifying the SSA makes debugging more difficult.