User Define Startup and End Blocks -- Normally the postprocessor will output the default startup Prep/G-codes checked on this panel at the beginning of the machine control data file. As for the end blocks, the postprocessor normally only outputs the tape trailer and the rewind start code at the end of the machine control data file. These options make it possible to create unique startup and end output blocks (see Start Prog and End Prog tabs). (Intcom 3483 and 3980)