Sending messages to terminals

Hi, In order to free up terminals for use while print requests are executed, I tend to instigate the running of reports from a 4GL program by performing a 'RUN' command and running the report in the background. However, there are occasions when impatient users try to go on and do something else they shouldn't until the report has finished. To counter this I am trying to come up with a way of determining how to get a message back to the users screen to let them know the report has finished, even though they may be in another program which does not reuqire them to wait for the report to finish. I know I can work out who sent the report and from which terminal, but the problem I forsee is how to get a message up on their screen and for them to interact with it, perhaps just by hitting 'return' in acknowledgement. Does anyone think this is a possibility and if so would you like to point me in the right direction. We are running RDS 4.2 on AIX. Cheers, Ian.