Heath, My two cents.

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BLI decoders (Paragon) only show up in BLI locomotives and the difference between steam and diesel can be determined. BLI has a common assignment for functions that they use.

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This is not the case for ESU decoders which could be in any manufacturer’s loco and the same decoder can be used for both steam and diesel. Just look at the differing use of functions among the loco manufacturers that use ESU decoders. Not to mention the difference between use of functions in the EU versus US.

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Mark Granville