struct PK_range_bound_s
    {
    PK_LOGICAL_t        have_upper_bound; --- (PK_LOGICAL_false)
    double              upper_bound;      --- upper bound on min separation
                                          --- (0.0)
    PK_LOGICAL_t        have_lower_bound; --- (PK_LOGICAL_false)
    double              lower_bound;      --- lower bound on min separation
                                          --- (0.0)
    };
typedef struct PK_range_bound_s PK_range_bound_t;




This structure is used to place upper and/or lower bounds on the separation
of objects.