NC Part program main and subroutine numbers
Cadfil Help contents 
Cadfil.com Home
(Please note that on most modern NC controllers program numbers are not required as the names of the .PAY or .CTL file used can be used directly for the main and sub-program names rather than numbers. In the case the .SM post processor configuration file is set so the user is not asked for program numbers.)
The user is prompted for the program numbers to use in the NC data. These are checked to ensure validity for the particular controller, the user being prompted until a valid input is supplied. The numbers supplied are whole numbers, and there usually being a range for valid numbers, for example 1 to 999 or 1 to 9999. On some controllers it may be possible to have the same main and sub-programs numbers, and other controllers may not permit this. There may also be certain program numbers on the machine that are reserved for special purposes. This is not checked for. The user is advised to read the documentation for the specific machine and controller used, and to be familiar with these. It is also advisable to keep a record of all user program numbers as they are used.