Omron CP - PROGRAMMING MANUAL 05-2007 Programming Manual page 703

Subroutines
Note
670
Subroutines can be nested up to 16 levels. Nesting is when another subrou-
tine is called from within a subroutine program, such as shown in the following
example, which is nested to 3 levels.
SBN 10 SBN 11
SBN 11 SBS 12
RET
RET
Main program
Subroutine
program n
Subroutine
program m
A subroutine can be called more than once in a program.
SBN 12
RET
Execution condition ON
Execution condition ON
Two-level
nesting
Program end
Section 3-18