This is a markup language heavily inspired by XML & HTML. I got rid of entities, added c-like escaping & comments, and some other stuff. The name ML666 was choosen, because I couldn't find an unclaimed 3 or 4 letter acronym, so I just took some number.
The Project Homepage, along with some prebuilt documentation, can be found at https://ml666-s.s.abrecht.li/.
For the formal syntax description, see docs/syntax.abnf and docs/syntax.xhtml.
For the semantics for parsers & tokenizers, see docs/semantics.md.
For an example, take a look at one of the files in the test/ directory, such as: test/example.ml666.