Head values in operating points are ignored for modes that calculate head based on other criteria (for instance, for selection modes where all heads are on the same design curve).

For data points other than the design point, specify what head values we wish to use. Options are, use the heads specified in the operating points themselves, calculate the heads on the selected design curve (based on specified flows), or calculate the heads based on the system resistance curve (also based on specified flows). If not this parameter is emtpy, will default to using head values specified in the points (which if not passed in, will be 0).