definiens: means an immunoglobin ( Ig)molecule, generally comprising four polypeptide chains, twoheavy chains ( H ) and two light ( L ) chains or an equivalent homologue thereof ( e.g. a camelid nanobody, whichcomprises only a H chain, single domain antibodies ( dAbs ) which can be either H or L chains ) ; including full lengthfunctional mutants, variants, or derivatives thereof ( including but not limited to chimeric antibodies, which retain theessential epitope binding features of an Ig molecule and including dual specific, bispecific, multispecific, and dualvariable domain Igs ; Igs ( e.g. IgG, IgE, IgM)of any class or subclass ( e.g. IgG1 ) and allotype . Also included within theterm Antibody is an Antibody fragment, which is a molecule comprising at least one polypeptide chain that is not fulllength