HEIDENHAIN TNC 620 (73498x-01) ISO programming - Manual (Page 200)

200 Programming: Subprograms and program section repeats
7.
5 Nesting
Subprogram within a subprogram
Example NC blocks
Program execution
1 Main program SUBPGMS is executed up to block 17.
2 Subprogram SP1 is called, and executed up to block 39
3 Subprogram 2 is called, and executed up to block 62. End of
subprogram 2 and return jump to the subprogram from which it
was called
4 Subprogram 1 is executed from block 40 up to block 45. End of
subprogram 1 and return jump to the main program SUBPGMS
5 Main program SUBPGMS is executed from block 18 up to block
35. Return jump to block 1 and end of program
%SUBPGMS G71 *
...
N17 L "SP1",0 * Subprogram at label G98 L SP1 is called
...
N35 G00 G40 Z+100 M2 * Last program block of the
main program (with M2)
N36 G98 L "SP1" Beginning of subprogram SP1
...
N39 L2,0 * Subprogram at label G98 L2 is called
...
N45 G98 L0 * End of subprogram 1
N46 G98 L2 * Beginning of subprogram 2
...
N62 G98 L0 * End of subprogram 2
N99999999 %SUBPGMS G71 *