I've used and created domain-specific languages before, plenty of times (e.g. using yacc/lex). Normally we'd start with grammar written in BNF, and a bunch of keywords. This is easy to do, easy to share.

Recently, I've started working with diagrammatic programming languages - closest parallel is circuit-diagrams in electronics, where it's very difficult to express ideas in text, but very easy to express them in wiring-diagrams.

This is a new and novel problem for me: how to efficiently express these mini-languages, and share concepts in them with colleagues?

(i.e. how to whiteboard-program within them. Actual programming is easy - you have physical components to hand)

Are there tools for this? Or good/best practices (e.g. equivalent of "always use BNF as starting point for your new DSL, and use tools like yacc to generate the parser, compiler, etc"). My googlefu is proving weak - all I get is false positives for wiring diagrams, and UML editors (since these are custom languages, UML doesn't seem to help)