Help:Lint errors/obsolete-tag

The obsolete-tag error is when deprecated HTML elements are used.

Since it is unclear to us at this time how far we want to push this goal of HTML5 compliance, this category is marked low priority. Some wikis might choose to not address this right away. Other wikis might want to get ahead and want to be HTML5 compliant. It is possible that some wikis might write bots to address this. So, please use your judgement and wiki-specific policies to guide you in how much effort you want to spend on this. If, in the future, there is greater clarity about pursuing this more aggressively, we will reflect that by updating the severity of this linter issue appropriately.

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. Examples of some "popular" html tags that had visual effects and have been removed from major browsers include  and. A further problem is that different browser vendors may remove them independently so editors or readers may have inconsistent views of the same page, leading to confusion.

Such removal of styling or unique treatment of html tags by browser vendors can happen at any time and without prior notice.