This macro populates an entity of type PK_LTOPOL_t with its null values. A null ltopol is a PK_LTOPOL_t with lattice=PK_ENTITY_null and ltopol=0. #define PK_LTOPOL_null_m(l) \ ( \ (l).lattice = PK_ENTITY_null, (l).ltopol = 0 \ )