Help:Lint errors/obsolete-tag

The obsolete-tag error is when deprecated HTML elements are used. Currently, the deprecated elements with their alternatives are:

Font sizes
The values above seven are equivalent to seven.

Rationale
Mediawiki currently whitelists these elements, and they tend to be output the same way as input. This means that when browser vendors decide to remove these they will simply display as regular undecorated text. Some "popular" html tags that had visual effects and have been removed from major browsers are  and. A further problem is that browser vendors may do remove them independently, so editors or readers may have inconsistent views of the same page, leading to confusion.

This removal can happen at any time and without prior notice.