HTML.ForbiddenElements TYPE: lookup VERSION: 3.1.0 DEFAULT: array() --DESCRIPTION--
This was, perhaps, the most requested feature ever in HTML Purifier. Please don't abuse it! This is the logical inverse of %HTML.AllowedElements, and it will override that directive, or any other directive.
    If possible, %HTML.Allowed is recommended over this directive, because it
    can sometimes be difficult to tell whether or not you've forbidden all of
    the behavior you would like to disallow. If you forbid img
    with the expectation of preventing images on your site, you'll be in for
    a nasty surprise when people start using the background-image
    CSS property.