Thrown when FlowSegment.FlowType is NOT TR55FlowSegmentType.FlowTypeChannel.
Remarks
This property only takes part in TR-55 calculation when FlowSegment.FlowType is TR55FlowSegmentType.FlowTypeChannel.
The unit of value is defined by the drawing unit in drawing settings (CivilDocument.Settings.DrawingSettings.UnitZoneSettings.DrawingUnits).
It's either Feet or Meters.