[coldtea]

>I don't think this really applies to this Mermaid library.

Well, it is easy to just read and understand what it talks about (as opposed to some more opaque format) and only has the bare minimum annotations needed beyond the text labels and node names.

>For a Markdown-like I would expect more of an ASCII-art like input, which would look like the rendered chart also in its ASCII form

I don't see much value in such a scheme (even though there does exist such a program), because to produce (and later edit/update) the ASCII-art would be as tiresome and evolved as producing the final graphic document.

I'd rather write e.g something like:

  label a = "start"
  label b = "end"
  a -> b

than draw 2 ascii art boxes, place the labels myself, and draw ascii art arrow between them.