Baseline.EntityStart: Returns the beginning station of the alignment entity at the current station (Line PI or curve PC station)
Baseline.EntityEnd: Returns the ending station of the alignment entity at the current station (Line PI or curve PT station)
These two functions would greatly enhance the power of the subassembly composer by returning the begin and end station of the alignment sub-entity at the current station. Combining this with the Baseline.Station function, the designer could build subassemblies which behave differently in curves and lines, as well as transitioning between the two.