你多才多艺，不但在高科技领域发明了一项新的能源技术或治癌药物，而且在低科技领域还发明了一双多功能袜子。你要申请美国专利时，你爱人帮你出了个二合一的注意，说亲爱的，为了省钱，你干吗不把高科技发明和多功能袜子放到一个申请里，权力要求1-10写上高科技，权力要求11-20写上低科技。这样的话，咱们家花一份申请费，就能拿到高低科技两套专利权。如果你没有主见，真的言听计从了。非常遗憾，美国专利局将来一看，会说你这是two or more independent and distinct inventions are claimed in one application，要求你分案申请(divisional application)，就是把高低分开，高科技发明一份申请一份费用拿一个专利，低科技发明另一份申请另一份费用拿另一个专利。这就好像你年轻的时候谈恋爱，和女朋友上电影院，你只想买一张票，女朋友坐到你腿上，然后你坐到一个座位上。你们那样做，虽然很温馨很方便很省钱，但电影院卖票的肯定不会答应。
这只是一个极端的或搞笑的例子，现实中认定 two or more independent and distinct inventions还是比较复杂的，与中国的单一性也有区别。有机会我们将举例说明。另外，美国国会认为“二合一”只是一个形式缺陷问题，几百美元的小事，因此严禁对此小题大做。
If two or more independent and distinct inventions are claimed in one application, the Director may require the application to be restricted to one of the inventions. If the other invention is made the subject of a divisional application which complies with the requirements of section 120 of this title it shall be entitled to the benefit of the filing date of the original application (高低科技共享原始申请日). A patent issuing on an application with respect to which a requirement for restriction under this section has been made, or on an application filed as a result of such a requirement, shall not be used as a reference either in the Patent and Trademark Office or in the courts against a divisional application or against the original application or any patent issued on either of them, if the divisional application is filed before the issuance of the patent on the other application(如果分案及时，高低科技互不作为 reference). If a divisional application is directed solely to subject matter described and claimed in the original application as filed, the Director may dispense with signing and execution by the inventor(手续上的照顾). The validity of a patent shall not be questioned for failure of the Director to require the application to be restricted to one invention (即使专利局走眼让你爱人的主意得逞，不可仅仅因此质疑专利有效性).