[kazinator]

No; these diagrams are not drawn from a semantic declaration language. They are drawn from ASCII diagrams. They are just inferring a "skin" made of nicer-looking Unicode symbols.

The examples don't show the source code next to them, but you can just view the page source in your browser (e.g. Ctrl-U in Firefox).

[kiitos]

So the purpose of the tool is to transform an ASCII diagram to a Unicode diagram? I struggle to understand the value of such a thing.

    +---+   +---+
    | A |-->| B |
    +---+   +---+

is actually better than

    ┌─┐ ┌─┐
    │A│→│B│
    └─┘ └─┘

because it can be manipulated without external tools. Right?