The -h switch applies only to A-Shell/UNIX and remote sessions connected via modem or telnet. When specified, the SIGHUP (hangup) signal is simply ignored. This was historically useful to allow a program (such as a posting program) to keep running even if its terminal connection was lost. However, its usefulness has been superceded by the default handling of SIGHUP, which properly turns the process into a background daemon.

Note that regardless of the way you choose to handle the hangup situation, you can also have A-Shell produce a trace log documenting when it receives such a hangup signal and what it did about it. See the discussion of miame.ini TRACE statement for more details.