This .NET class wraps the AcGiViewportTraits ObjectARX class. 

Viewports, on both Model and Layout tabs, now receive a call to their Viewport.SetAttributes() method before Viewport.WorldDraw(), similar to entities. This gives viewports the opportunity to pass per-viewport properties to the display and rendering systems. 

A concrete instance of this interface class is passed to both Viewport.SetAttributes() and ViewportTableRecord.SetAttributes(). Set calls on this interface should then be made by the viewport object. 

This class derives from DrawableTraits.

Autodesk.AutoCAD.GraphicsInterface.SubEntityTraits
    Autodesk.AutoCAD.GraphicsInterface.DrawableTraits
        Autodesk.AutoCAD.GraphicsInterface.ViewportTraits

Public abstract Class ViewportTraits
Inherits DrawableTraits

public abstract class ViewportTraits : DrawableTraits;