Sorry for the late answer.

I think letters for basic metrics is fine, but for more complicated signals it gets tricky. It's like coding without comments, it looks like fine when you first write it, but then you get back to it a few days later and you think "damn, where the hell is my doc ?" (a ...

I'm using circuit network to manage my oil processing with basic rules.

I wish I could use process icons as signals
icons like these:
https://wiki.factorio.com/images/Light_oil_cracking.png https://wiki.factorio.com/images/Advanced_oil_processing.png

I could output those recipe icons on my ...