struct PK_FACE_neutral_causes_array_s
    {
    int          n_causes;    --- Number of face causes in array
                              --- (equal to number of faces in neutral sheet)
    PK_FACE_neutral_causes_t
                *face_causes; --- Set of face causes
    };
typedef struct PK_FACE_neutral_causes_array_s PK_FACE_neutral_causes_array_t;




This data structure contains an array of PK_FACE_neutral_causes_t
structures.



Each element of the array contains the tracking information for one
face of the coreesponding neutral sheet.  The length of the array is
n_causes and this is the number of faces in the corresponding
neutral sheet.