Buff Condition?

I'm almost sure I have read about being able to compare if units have a certain buff, but I have looked for it for quite some time, and I can't find it, so what I wonder is, is there any such comparison, and if there is, where do I find it, and do I need to use JASS or some other editor than the normal one.

An easily made mistake.

Its under boolean. (I know its counter-intuitive, dont ask me)

Thanks, really made stuff with multi-level spells much easier, now, perhaps I will get done with my map within just a month or so...