Each brep loop has a defined type, e.g. outer, inner or point on surface.
RhinoCommon (in RhinoCommon.dll)
Public Enumeration BrepLoopType
Unknown loop type.
2d loop curves form a simple closed curve with a counterclockwise orientation.
2d loop curves form a simple closed curve with a clockwise orientation.
Always closed - used internally during splitting operations.
"loop" is a curveonsrf made from a single (open or closed) trim that
has type TrimType.CurveOnSurface.
"loop" is a PointOnSurface made from a single trim that has
Rhino for MacSupported in: 5.4
Rhino for WindowsSupported in: 6.26