Omron SYSMAC CJ - REFERENCE MANUAL 08-2008 Reference Manual page 852

Subroutines
812
subroutine is completed, program execution continues with the next instruc-
tion after SBS(091).
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
RET
Execution condition ON
Main program
Subroutine
program
(SBN(092) to
RET(093))
Program end
SBN 11 SBN 12
SBS 12
RET
RET
Section 3-19