An #INCLUDE file writes an external source file into a Production Reporting report specification. Use #INCLUDE files to keep commonly-used routines in a single file and reference or "include" that file in programs that use the routine.
For example, you might have a set of #DEFINE commands for different printers to control initialization, font changes, and page size declarations. In this case, you could reference the appropriate #INCLUDE file depending on which printer you want to use.