(a)
If two or more independent and distinct inventions are claimed in a single application, the examiner in an Office action will require the applicant in the reply to that action to elect an invention to which the claims will be restricted, this official action being called a requirement for restriction (also known as a requirement for division). Such requirement will normally be made before any action on the merits; however, it may be made at any time before final action.
(b)
Claims to the invention or inventions not elected, if not canceled, are nevertheless withdrawn from further consideration by the examiner by the election, subject however to reinstatement in the event the requirement for restriction is withdrawn or overruled.
Code of Federal Regulations
[24 FR 10332, Dec. 22, 1959, as amended at 62 FR 53195, Oct. 10, 1997; 72 FR 46842, Aug. 21, 2007; 74 FR 52691, Oct. 14, 2009]