typedef int PK_LOOP_type_t;
PK_LOOP_type_vertex_c loop is just a vertex without any edges
PK_LOOP_type_wire_c loop has no interior, e.g. from a wire body
PK_LOOP_type_outer_c simple peripheral loop
PK_LOOP_type_inner_c loop is a simple hole
PK_LOOP_type_winding_c winding loop on a periodic surface
e.g. a circle on a cylinder or doughnut
PK_LOOP_type_inner_sing_c loop is a hole around the surface singularity
e.g. chopping the top off a cone
PK_LOOP_type_likely_outer_c an apparently peripheral loop on a doubly
closed surface
PK_LOOP_type_likely_inner_c an apparent hole in a doubly closed surface
PK_LOOP_type_unclear_c a loop dividing a periodic degenerate surface
in two ( contains just one pole )
PK_LOOP_type_error_c invalid loop or algorithm failure
