struct PK_BODY_problem_group_s
    {
    PK_BODY_sewing_problem_t     type;
    PK_EDGE_t                   *edges;
    int                          n_edges;
    };

typedef struct PK_BODY_problem_group_s PK_BODY_problem_group_t;




A structure collecting a set of edges associated with an encountered sewing
problem, together with a token identifying the type of problem ( if known. )


This structure embodies information on a group of edges encountered during a
sewing operation that could not be successfully processed. The problem may be
due to options set that prohibited the processing, or an internal limitation
that prevented selection of a subset of the edges that could be glued together.

The structure has three user fields:

    type:    A token of type PK_BODY_sewing_problem_t that can be one of ...

             PK_BODY_sewing_overlapping_c    The group of edges represent the
                                             boundaries of an area where sheets
                                             overlap to an extent too large to
                                             permit glueing them together

             PK_BODY_sewing_non_manifold_c   The group of edges represent the
                                             boundaries where a collection of
                                             more than two sheets meet along a
                                             'common' edge

             PK_BODY_sewing_non_oriented_c   The group of edges are those that
                                             if sewn together would introduce a
                                             twist into the resulting sheet
                                             body.

             PK_BODY_sewing_unspecified_c    The group of edges are where the
                                             algorithm couldn't decide how to
                                             sew them up and wasn't able to
                                             figure out what the problem was

    n_edges: The number of edges associated with the problem
    edges:   An array of those edges.