Requesting that a control function be performed.
Permitted control functions are:
- DEFAULT
- to set the task's current working directory.
- SETENV
- to set the value of an environment variable in the
task's process.
- PAR_RESET
- to reset all parameters, or parameters of a named
action in a monolith, back to the `ground' state.
For a discussion of parameter states, see
SUN/114.
N.B. DEFAULT and SETENV are required because tasks are
run in separate processes, therefore (under Unix anyway) changing the current
working directory or environment variables of the controlling process will
not alter them for any existing subsidiary tasks.