error occurred.
OBJ_nid2ln() and OBJ_nid2sn() returns a valid string or B<NULL>
on error.
OBJ_obj2nid(), OBJ_ln2nid(), OBJ_sn2nid() and OBJ_txt2nid() return
error occurred.
OBJ_nid2ln() and OBJ_nid2sn() returns a valid string or B<NULL>
on error.
OBJ_obj2nid(), OBJ_ln2nid(), OBJ_sn2nid() and OBJ_txt2nid() return