It would be more efficient to be able to see the station limits of parametric constraints graphically on screen with a control line in plan view and be able to change these stations and values dynamically similar to point controls. The only option now is to go through Corridor Objects which can be slow to process and missing information.
This should also allow showing persist snaps in plan and in the parametric constraints table (two new columns) if these are used when defining start / end stations.