Portable Infobox is an XML-like markup language created by Wikia. Its intended purpose was to make infoboxes render more cleanly on both mobile and desktop devices. The use of Portable Infoboxes has been heavily controversial, with Wikia known to desysop local administrators and forcefully implement migrations against community consensus.
On Miraheze, an open source fork of Portable Infoboxes was created to work with newer MediaWiki versions. The extension can be downloaded here. On The Sims Wiki on Miraheze, we only intend to use Portable Infoboxes for backwards-compatibility with templates that have been migrated. We do not expect to use the markup language here.