physical
How much of the guide path the vehicle covers, in the network's own length units, when it is sized by length rather than by whole zones. Null means it is sized in zones.
Passed straight through to the body. It is here for the same reason the passive transporter has it -- a vehicle that fits inside a zone gets its own length back when it reverses out of a dead end -- and it is here at all so that the two paradigms can model the same vehicle. A feature only one of them had would make any comparison between them a comparison of the feature.