DEFUSER command image [routine]
Define a command which calls a user written subroutine in a shareable image.
The subroutine should have a single character string parameter in which it will receive the ICL command line parameter string. The string is received as typed, except for the substitution of bracketed expressions.
Typing command causes the shareable image to be activated dynamically
(if it is not already loaded), and the subroutine to be called. The
subroutine can return an error message to ICL by signalling a VMS condition.
This will result in the ICL exception USERERR. The exception text will
contain the message associated with the VMS status returned.
ICL The Interactive Command Language for ADAM