Which of the following statements characterizes idiotypic determinants?

The idiotype is defined as the specific region of the Fab poion of the Ig molecule to which antigen binds. Antibodies against the idiotype poion of an antibody molecule are called anti-idiotype antibodies. The formation of such antibodies in vivo during a normal B cell antibody response may generate a negative signal to B cells to terminate antibody production. Variable regions (VL and VH) constitute the antibody-binding (Fab) region of the molecule. Within the VL and VH regions are hypervariable regions (extreme sequence variability) that constitute the antigen-binding site unique to each Ig molecule.