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.
@Khaled: Thanks!
