That's a valid workaround. However, NUL seems to perform faster than -k to return/noop or the like (admittedly I only did some *rough* tests).
In any case, my main concern was to maintain consistency, if possible. That is, compatibility of existing scripts, without constrains to the improvements of v7+.
While I cannot assess whether or not there are scripts that used NUL other than in /filter, I myself used it in the /filter command only, hence I am happy with the sollution proposed by Khaled.
Everyone knows that this solution will not solve the problem. If you make NUL global it will override a NUL alias. NUL is not part of the interpreter. It's behavior is unpredictable. It's like using $mircexe:NULL. It may work. It may not. Depends on how the user has it installed. You leave the NUL object in and it WILL lead to future hardships down the road.
Consistency is key to scripting. Consistency of the language and how it performs in every situation. This goes against that.
If you are concerned about speed then don't use /filter for reading files. And speed is pretty irrelevant these days...
