##### Execution Mode

To explicitly indicate that a command should run in the operating system, precede the command with a dollar sign (`$`). This avoids command ambiguity. For example, typing `HELP` at the NeXtMidas prompt invokes the NeXtMidas `HELP` command, but `$HELP` invokes the help facility of the operating system.

To indicate that a command should run in the operating system while staying inside the NeXtMidas shell, use double dollar signs (`$$`) before the command name. Otherwise, the NeXtMidas shell temporarially exits while the operating system runs the command. (Within a graphical shell such as `SHELLGUI`, this is the default execution mode for all operating system commands.)