Crazy foreign logical operator I've stumbled across

Hey guys,

I’ve been working with some source I found online for a scrolling menu, and I happened upon this little ditty I don’t understand:

if (_x <- (width + 0.5 * (_root.pix_separate))) 
{
	_x = 0;
}

What’s the “<-” operator about? I replaced it with the less-than-or-equal-to guy thinking the author mis-typed (even though it functions as it should), and that definitely was not the case as doing so did some pretty major damage (well, damage in so far as it didn’t function at all). Could somebody with any kind of knowledge enlighten me?

Thanks,
TheRiddler