If two or more independent and distinct inventions are claimed in one patent application, the Commissioner of the USPTO may require the application to be restricted to one of the inventions. The inventor elects to prosecute one of the two inventions, and the unelected invention is abandoned and becomes a part of the public domain unless the inventor files a divisional application to protect the unelected invention.

The divisional application is a copy of the original application and is accompanied by a preliminary amendment that cancels the claims directed to the elected invention so that the claims of the unelected invention remain for examination.