15 U.S.C. § 1056: Disclaimer of unregistrable matter

(a) Compulsory and voluntary disclaimersThe Director may require the applicant to disclaim an unregistrable component of a mark otherwise registrable. An applicant may voluntarily disclaim a component of a mark sought to be registered. (b) Prejudice of rightsNo disclaimer, including those made under subsection (e) of section 1057 of this title, shall prejudice or affect the applicant’s or registrant’s rights then existing or thereafter arising in the disclaimed matter, or his right of registration on another application if the disclaimed matter be or shall have become distinctive of his goods or services.