ArcGIS Pro 2.6 API Reference Guide
Normal Property

ArcGIS.Core.CIM Namespace > CIMVoxelPlane Class : Normal Property
Gets or sets the direction vector of the plane, which is a unit vector representing the normal to the plane.
Syntax
public MapPoint Normal {get; set;}
Public Property Normal As MapPoint
Remarks
This vector is perpendicular to the plane you are defining, and it points in the direction of what you want to remove with the plane. The X, Y, and Z values should all be between 0 and 1. For example a Normal of (0,0,1) is pointing away from the earth's surface, and this defines a horizontal plane.
Requirements

Target Platforms: Windows 10, Windows 8.1, Windows 7

See Also

Reference

CIMVoxelPlane Class
CIMVoxelPlane Members