The INCLUDE directive "stacks" the current source file and begins reading tokens from the source file given by the FileName argument. If you use the INCLUDE directive, you need not repeat a sequence of statements that are common to several source files.
Syntax
INCLUDE FileNameRemarks
The assembler uses the following search order when attempting to open the INCLUDE file:
When the file named in the INCLUDE directive is located, the assembler opens it and assembles all of the statements contained therein until the end of the file is reached. The file is then closed and assembler resumes in the original module at the line following the INCLUDE directive.
An INCLUDE file should not contain an END assembler directive to denote the end of the included module; the assembler closes the included module when its physical end of file is reached.
INCLUDE files may be nested to any reasonable level, and is limited only by the operating system's ability to provide the necessary resources.
INCLUDE OS2.INC