How to use a dummy control section

A dummy control section (dummy section) lets you write a sequence of assembler language statements to describe the layout of data located elsewhere in your source module. The assembler produces no object code for statements in a dummy control section, and it reserves no storage in the object module for it. Rather, the dummy section provides a symbolic template or mapping that is empty of data. However, the assembler assigns location values to the symbols you define in a dummy section, relative to its beginning.

Therefore, to use a dummy section, you must:

Have access to a storage area for the data
Ensure that the locations of the symbols in the dummy section correspond to the locations of the data being described
Establish the addressability of the dummy section in combination with the storage area

You can then refer to the data symbolically by using the symbols defined in the dummy section.