Well I should have been a bit more clear. mIRC doesn't support tabs, but that doesn't mean other clients don't. All of the Linux clients I know of parse tab codes, and therefore I'd assume their Windows versions (specifically XChat, and BitchX) do as well. I also tested a bunch of Windows clients I have laying around on my harddrive

.IRC, HydraIRC, and Klient support tabs. The only Windows client I tested (other than mIRC) that did not support tabs was Bersirc. So while mIRC doesn't support this, the majority of other chat clients do.

But like I say, I see no reason why this can't be strip-able just like bold/underline/reverse/color codes are. It could be a rather advanced system.

"Tab settings:
[ ] Strip tab characters
[ ] Treat tab characters as [.........] spaces
[ ] Enable tab support
[ ] Do not process tab characters"
That gives you as much control as you could need. The first setting strips all tabs, the second translates a tab character to a series of spaces, the third treats it as a true tab character, and the last keeps it the way it is (displaying a box character)". That solves all potential flooding problems. If you are afraid of floods, you can either strip the codes, do not process the codes, or even set it to translate a tab into a single space character.