A2: Intrinsic coordinates have been made optional in RTM 1.1. In the location package, the intrinsic coordinates have been moved from the AssociatedNetElement to a daughter class, the use of which is optional. It is always possible to refer to other positioning systems instead.
On the other hand, in the Topology package, the extremities of (linear) NetElements need to be differentiated (disambiguated) in some way. This is why the corresponding intrinsic coordinates (0 and 1) of PositioningNetElements must refer to some coordinate, in the POsitioningSystem package.