I just tried it on Pocket, and it keeps switching me to the web version... which is a bit frustrating, since the source code / DocBook [1] XML format looks ideal for describing a Pocket article.

Seems DocBook has been around since 1999, judging from when the first O'Reilly book was published about it [2].

I just flagged it with the Pocket app's "Report An Article Display Problem" feature, but it is such a niche use case that I can't imagine them spending time on it.

[1] https://en.wikipedia.org/wiki/DocBook

[2] https://www.oreilly.com/openbook/docbook/book/docbook.html