Please see http://www.schirmacher.de/pages/listundefinedpages.action?key=INFO for a list of undefined pages. These pages come from some text within

tags in square brackets.

If the rendered representation of the content does not show the "link to an undefined page" (the link with the small plus icon), then the text between the square brackets should not be listed as undefined either.

There is also some text in curly brackets (a macro) which is also listed as undefined.