Other question about normals

Hello I am trying to calculate the normal to a surface belonging to a solid, (a Box in my test). The calculus of the normal is done in a point belongining to an edge that belongs to the surface. Solid > Surface > Edge > Vertex. The point for me is to know how to get the orientation of the normal regarding to the box. which means is it directed inside or outside the Box ? What i tried is the following : 1) looking for edges shared by more than two faces, 2) For these faces getting the parameters of the edge regarding theface

BRepTools::UVBounds(aFace, anEdge, Umin, Umax, Vmin, Vmax); 3) I declare a Local Property Geom with the geometrical surface of the Face

GeomLProp_SLProps LPropSurf(aGeometricSurface, Umin,Vmin,1, Precision::Confusion()); 4) Finally i Get the Normal this way

Normal = LPropSurf.Normal(); 5) I finally construct an edge with the normal 6) i don't know how to test the orientation of this edge in regard with the solid ???? Can any one help me ? Thank you