Rockwell Automation GMLC Reference Manual - Manual (Page 381)

Publication GMLC-5.2 - November 1999
344 Multitasking Blocks
When starting multiple tasks, make sure that each task has a unique task
number. Task numbers should not be re-used until the current task using
that number is stopped (see Stop Current Task and Stop Other Task).
Otherwise, unexpected program execution and machine operation may
occur.
Sometimes it is necessary to loop program flow to the beginning of a task.
When you do this, be sure to make your connections at the correct point in
your program. For example, the following diagram loops program flow
for each of two tasks back to the beginning of that task: