[DefaultValue(0)] public int PortSpot {get; set;}
[DefaultValue(0)] public int PortSpot {get; set;}
This inherited property is initialized in the InitializeTreeNodeValues method. A value of GoObject.NoSpot will cause SetPortSpots to assign a Northwoods.Go.GoPort.FromSpot based on the parent node's GoLayoutTreeNode.Angle. If the value is other than NoSpot, it is just assigned. When Path is GoLayoutTreePath.Source, the Northwoods.Go.GoPort's Northwoods.Go.GoPort.ToSpot is set instead of the Northwoods.Go.GoPort.FromSpot.
This just gets or sets the RootDefaults's property of the same name.