That's a good point. Another suggestion besides (or in addition to) a $cmdprefix identifier would be some kind of $command identifier for the ON INPUT event specifically. This would return whether or not mIRC is about to process the line as a /command, abstracting the common

Code:
ON *:INPUT:*:if (/* !iswm $1- || $ctrlenter) ...


to:

Code:
ON *:INPUT:*:if (!$command) ...

- argv[0] on EFnet #mIRC
- "Life is a pointer to an integer without a cast"