Overview
RatingCurves.xml is a standard file (i.e. it has a fixed name) which contains all the rating curves used in your system. The rating curves can be used in transformation module to convert a stage to a discharge and vice versa.
A rating curve is referenced by the location id, i.e. each location has a specific rating curve for that point in the river.
A rating curve has a valid period specified with a start date and optionally with an end date.
It is possible to have different rating curves with the same location id and different valid periods . The valid periods can overlap. A rating curve is valid until the next rating curve with the next start date becomes valid.
When the transformation module needs to use a rating curve for a given location at a given system time, it will use the rating curve that has the system time in its valid period.