Shared Data Areas 

For the sake of completeness, this section describes a technique that allows you to access the global data of the calling program from an external subroutine. To do this, you declare a common data area for the calling program and the program containing the subroutine. All interface work areas declared using TABLES and NODES behave like the common data area.

Like external subroutines themselves, you should use common data areas very sparingly. The rules for accessing common data areas can become very complicated if you call function modules from nested subroutines.

You declare a common data area in all programs concerned using the statement:

DATA: BEGIN OF COMMON PART [<name>],

        
      END OF COMMON PART [<name>].

Between the two DATA statements, you declare all of the data you want to include in the common data area.

The common part declaration must be exactly the same in all of the programs in which you want to use it. It is therefore a good idea to put the declaration in an include program.

You can use several common parts in one program. In this case, you must assign a name <name> to each common part. If you only have one common part in each program, you do not have to specify a name. To avoid conflicts between programs that have different common part declarations, you should always assign unique names to common parts.