Omake
From Sasara
Omake is a Japanese term, commonly used by magazines and art books to denote "bonus" or "extra" material.
Rubenerd employed the term for his omake.xml and earlier omake.opml files. These used XML formats, and XSLT to render them. Browser vendors have signaled they'll likely retire XSLT, probably because its too open, extensible, cross platform, and useful for the modern Web. As such, Ruben begrudgingly retired it.
Much of the material from this Omake has made it onto this wiki. It may be a blessing in disguise; wikis are far more flexible and offer more formatting options than a simple collapsible outline. He'll still miss it, though.