The case of A-Shell/Unix with the /after or /next switches is the most similar to the AMOS Task Manager. The task is submitted to the Unix at manager, which, like the AMOS Task Manager, keeps track of it in a queue until it launches it at the specified time. The process will run with the same login identity and environment as the process that submits it, but since it runs as a child to the at manager, it is independent of the original submitter (and thus not subject to becoming a zombie.) As in the prior case, all output that would otherwise have gone to the screen is sent to the LOG file instead.
The at manager is similar to the more familiar cron manager, both of which can be found on almost any Unix system. The cron manager is more suited to tasks that are to be run at regularly scheduled intervals; you submit jobs to it via the crontab command. The at manager, on the other hand, is more suited to jobs that are to be run once at a specified time in the (immediate or distant) future. To submit jobs to be run by the at manager, you can use the Unix at command. SUBMIT.LIT just acts as a front-end to at to allow you to use the simpler AMOS command syntax.