When you modularize source code, you place a sequence of ABAP statements in a module. Then, instead of placing all of the statements in your main program, you just call the module.

When the program is generated, the source code in the modularization unit is treated as though it were actually physically present in the main program. Source code modules help you to avoid repeatedly writing the same set of statements and to make your programs easier to read and understand. They are not used to modularize tasks and functions. You should use procedures for this purpose.