definiens: means : 1.22.1 an immunoglobulin ( Ig ) molecule, generally comprising four ( 4 ) polypeptide chains, two ( 2 ) heavy ( H ) chains and two ( 2 ) light ( L ) chains, or an equivalent Ig homologue thereof ( e.g., a camelid nanobody, which comprises only a heavy chain, or single domain antibodies ( dAbs ) which can be either heavy or light chain ) ; including full length functional mutants, variants, or derivatives thereof ( including but not limited to chimeric, veneered, humanized antibodies, fully human equivalents ( e.g. created by guided selection or similar technology ) ), which retain the essential epitope binding features of an Ig molecule, and including dual specific, bispecific, multispecific, and dual variable domain immunoglobulins ; Immunoglobulin molecules can be of any class ( e.g., IgG, IgE, IgM, IgD, IgA, and IgY ), or subclass ( e.g., IgG1, IgG2, IgG3, IgG4, IgA1, and IgA2 ) and allotype ; or 1.22.2 a molecule comprising at least one ( 1 ) polypeptide chain that is not full length, including ( a ) a Fab fragment, which is a monovalent frag ment consisting of the variable light ( VL ), variable heavy ( VH ), constant light ( CL ) and constant heavy 1 ( CH1 ) domains ; ( b ) a F(ab')2 fragment, which is a bivalent fragment comprising two ( 2 ) Fab fragments - 3 - DB1/ 86201718.40 linked by a disulfide bridge at the hinge region ; ( c ) a heavy chain portion of an Fab ( Fd ) fragment, which consists of the VH and CH1 domains ; ( d ) a variable fragment ( Fv ) fragment, which consists of the VL and VH domains of a single arm of an antibody, ( e ) a domain antibody ( dAb ) fragment, which comprises a single variable domain ; ( f ) an isolated complementarity determining region ( CDR ) ; ( g ) a Single Chain Fv Fragment ; ( h ) a diabody, which is a bivalent, bispecific antibody in which VH and VL domains are e xpressed on a single polypeptide chain, but using a linker that is too short to allow for pairing between the two ( 2 ) domains on the same chain, thereby forcing the domains to pair with the complementarity domains of another chain and creating two ( 2 ) anti gen binding sites ; and ( i ) a linear antibody, which comprises a pair of tandem Fv segments ( VH -CH1 -VH - CH1 ) which, together with complementarity light chain polypeptides, form a pair of antigen binding regions ; and ( j ) other non -full length portions of hea vy and/or light chains, or mutants, variants, or derivatives thereof, alone or in any combination