[lawtalkinghuman]

Not really since it's true. It isn't markup, it's a configuration file format.

"<em>This</em> is a markup language" since there is text which is marked up.

YAML/JSON is a way to serialise fairly common data structures (arrays/lists, hashes/dictionaries, numbers, strings, bools, etc.)

Incidentally, if you can seamlessly replace XML with something like JSON, then you probably aren't using the 'markup' bit of XML.

[ashtonkem]

Ah, yes, that’s totally correct. I was mentally glossing over the difference between markup and configuration languages.