Check to see if an object has been updated

I would like in a CL to see if a PF has been updated. Since when? So you
set a start time to compare against, kept in a message queue perhaps.

and each time it has been updated you move that date time to that message
queue.

DSPoBJD using the outfile will tell me the change date, as i see it, i can
save that outfile and compare each time, the change datetime.

is there a more sophisticated way. the reason I am asking is I would
rather than use a trigger
just have my cl run in the background and check if the file has been
updated every few minutes.