Index of a segment that can be considered the most important. Revit attempts to preserve the orientation of this segment when a Rebar instance changes its RebarShape to one with a different number of segments. 
   Namespace:   Autodesk.Revit.DB.Structure  
  Assembly:   RevitAPI  (in RevitAPI.dll) Version: 2015.0.0.0 (2015.0.0.0) 
  Since:  2012 
Syntax
Exceptions
| Exception | Condition | 
|---|---|
| Autodesk.Revit.Exceptions ArgumentException | When setting this property: majorSegmentIndex is not between 0 and NumberOfSegments. |