This was added in r67606 (https://www.mediawiki.org/wiki/Special:Code/MediaWiki/67606) as an optional support for Okawix formats (it lives now as 93e009a802151bfee1ecafde12d79c6aa2c0a37e)

If Okawix rendering is dead, we should probably remove the support altogether.

Seems like they wanted to move to ZIM (http://blog.wikiwix.com/en/2011/04/03/okawix-for-pc-soon-to-work-with-zim/comment-page-1/#comment-8042).

Anyway, torrent server is not reachable (http://91.121.92.45/zeno/pl.wikipedia.okawix.torrent), so may be the project is dead?

This should not be implemented or removed:

• Okawix does not use any clearly open defined format
• Okawix solution is based on an old version of the ZIM format packed in some kind of tar file.
• Okawix is neither maintained nor further developed
• Okawix is the only reader for its own format
• Okawix format does not provide any advantages in comparison to the existing ZIM format.

Change 129929 had a related patch set uploaded by saper:
Remove okawix/ZENO support

https://gerrit.wikimedia.org/r/129929

Change 129929 merged by jenkins-bot:
Remove okawix/ZENO support

https://gerrit.wikimedia.org/r/129929

Merged, reopen if there are other remnants in the code.