TL;DR
Simple tokens with all circuit network symbols.Very cheap.
What ?
I know we can translate any output signal into another with combinators, but for some simple designs, it could be useful to have "real" token, that generates specific signal. I mean, we can "read" from chest signals like "iron plate" or "wood", but not [1], [X], or [RED]. We can set those signals in Constant Combinator, but it's often to many wiring to use it properly and dynamically change.Why ?
I was creating system that toggles train between three unloading stations. First train goes to first station, 2nd to 2nd and so on in cycleThe simplest way is to use chests with some kind of token and inserters connected to Rail Signals. I need to put SOMETHING into the chest, and I found it silly to use eg. wooden logs as a signal to control signals. For such designs, tokens with predefined symbols (eg. [GREEN]) makes more sense. I also found that such simple "analog" designs, with minimal wiring and combinators, works much better and more reliable than any combinators designs...
Such tokens can be also put into train, and be read be destination station to perform some action...