18 U.S.C. Sec. 1028(D)(5) is the definition of a "False Authentication Feature." This law defines a False Authentication Feature as any "unique identifying number, mark, or imprint, or other feature, or combination of features, that is used to falsely authenticate a document or to conceal the true authenticity of the document." Different types of False Authentication Features may include but are not limited to unique serial numbers, watermarks, holographic seals, and other features used to authenticate documents.