Now, I can (and do) blueprint seven combinator paths each checking for and emitting a unified signal for one type of locomotive, then work on that. As long as I pre-filter for the position I want in each, it works reliably, because you can't have two locos in the same spot. It is an invitation to error, though, especially if you add a new type of locomotive to an existing system. Gotta update all those stations with more combinators, and make sure they have the correct position values.
Also, detecting LCCCCL vs LLCCCC vs CCCCLL trains.... fun times. If I introduce a new "long distance transshipping" model, as I'm thinking of doing, that'd also mean separate blueprints for the LCCCCL-LCCCCL-LCCCCL-LCCCCL combination that'll ensure we run right on through anything standing on the tracks instead of getting eaten. If the circuit network uncouple/couple mod works, and I build those from local trains on demand, instead of a dedicated network, that'd mean the wagon location variants become more of a thing....
I believe it would be reasonable, and useful, for the LTN output to also emit a "generic" signal for:
- locomotive (any type) encoded position
- cargo wagon (any type) encoded position
- fluid wagon (any type) encoded position