PK_ERROR_code_t  PK_SURF_ask_part
(
--- received arguments ---
PK_SURF_t        surf,              --- a surface

--- returned arguments ---
PK_PART_t *const part               --- owning part (possibly PK_ENTITY_null)
)


This function returns the part which owns the given surface, if there is one,
otherwise PK_ENTITY_null.


The part will be returned if the surface is used directly or indirectly
anywhere in its definition:
    either by being attached directly to a face,
    or as construction geometry attached to the part.
    or by being used in the definition of other geometry in the part.