Stop

class Stop @JvmOverloads constructor(val system: FleetSystem, val location: String, name: String? = null) : ModelElement(source)

A permanent place where loads wait to board whatever comes by.

The second of this subsystem's two waiting lines, and the one that exists because of a real difference rather than a convenience. A load that posts a transport request waits for a decision: some vehicle will be told to come for it, and the dispatcher's queue measures how long that took. A load standing at a stop waits for no decision at all. It waits for the next vehicle that comes past with room and somewhere useful to go, which is a function of headway and capacity. Putting it in a queue whose time in queue means "wait for a decision" would report a quantity that does not exist (A11).

So a stop owns its own waiting line and reports it separately. The two are both real and must not be summed: one answers how long work waits to be allocated, the other how long a rider waits for a service to turn up.

A stop is permanent and a TourStop is not. A TourStop is per-tour execution state -- a place to be and something to do there -- and it names a location. A Stop is a model element that outlives every tour, owns the waiting area, and is what per-stop statistics belong to. The two are joined by the action: a boarding action holds the Stop it draws from. Three things follow, all of them wanted:

A vehicle collecting a posted load needs no Stop. It collects at an arbitrary junction that nobody waits at, so requiring one per tour stop would make every such pickup declare a waiting area that never holds anybody.
The reference is an object rather than a name, so a boarding action cannot be pointed at a stop that does not exist.
Two lines may share one stop, which is what makes an interchange, a transfer point and a shared drop point expressible without any of them being a feature.