Prep Code That Establishes UPM -- The prep code that establishes UPM mode (either IPM or MMPM) for this machine (usually 94). If this machine has only inverse time feed available, or if neither IPM nor MMPM are available, enter NA (not available). If the prep code is not available, the postprocessor converts the feedrate to the appropriate feedrate code required by the machine. (Intcom 508)