As you may know, while testing NCL procedures it is necessary to unload the prior version of the procedure from memory each time the proc is run so any new changes will be picked up from a newly editied version. This is done by issuing the following command from the Command Entry screen:
UNLOAD PROC=procname
A handy way to do this automatically during testing is to include the following as the first line in your procedure:
UNLOAD PROC=&0
Variable &0 (that's a zero) evaluates to the name of your procedure, so every time the procedure is run after making changes, the prior version is automatically unloaded from memory without having to issue the UNLOAD command manually in Command Entry. Any changes you make will be included each time you run the procedure. Once you are done testing your NCL procedure and everything is working the way you like, you can simply remove the UNLOAD command from the procedure.