For those wishing to freely allow HTML in Dokuwiki
Have a look at
htmLawed, a highly customizable, 45 kb, single file, non-OOP PHP script to filter and purify HTML. Besides restricting tags/elements, attributes and URL protocols as per one's specification, and balancing HTML tags and ensuring valid tag nesting/well-formedness, it also has good anti-XSS and anti-spam measures.