Existing cant annotation is often, if not always, required on profile drawing.

Actually we must project rails onto the profile, create aliases, to extract level differences between existing rails whereas the information is fully available from regression points.

We should be able to annotate existing cant from regression points similar to slew and lift/lower, including using interpolated value if annotation done at regular interval.

BTW, we should (must) be able to manage sign of existing cant in regression points to ensure proper information and that user has control on the information?