This is an inbuilt function function provided by PPWIZARD.
PPWIZARD macros utilize a buffer to hold lines that they generate, these are read before the file is accessed. This function allows you to add data to be processed next.
The function takes a single parameter which is the line or lines (for multiple lines they should separated with a newline character).
This routine is handy where you may have captured some text, including references to macros etc and you wish to process the data where the data might otherwise be written directly to the output file.