Begin Subroutine }n

See also M99 End Subroutine

}n:

The subroutine number

This command must be the first line of a subroutine.

All subroutine code must start with }n and end with m99:

}2 (sub 2 begin)
some code
.
.
.
end of code
m99 (sub end)

Instructions for using external sub-routines are available here.