isignore -- if v1 is a user in your ignore list with the ignore switch v2 (v2 optional)
This is not working on 7.34, even
this page documents it will work, it might have worked in the past but as of mIRC 7.34, you must specify the type and not the switch:
if (foobar isignore c)
;must be for example:
if (foobar isignore channel)