Revit 2017 APIArc..::..XDirection Property Arc Class See Also Returns the X direction.Namespace: Autodesk.Revit.DBAssembly: RevitAPI (in RevitAPI.dll) Version: 17.0.0.0 (17.0.484.0)SyntaxC#public XYZ XDirection { get; }Visual BasicPublic ReadOnly Property XDirection As XYZ GetVisual C++public: property XYZ^ XDirection { XYZ^ get (); }See AlsoArc ClassAutodesk.Revit.DB Namespace