Certain U.S. patentability rules are related to the filing date of the U.S. patent application. The term "filing date" refers to the effective filing date of the earliest U.S. patent application filed by the inventor(s) containing a disclosure that supports the claimed invention. The application in which the invention is disclosed must meet the requirements for being either (1) a "first" filing, (2) an earlier-filed, related "parent" application of a later-filed continuing (continuation or continuation-in-part) application in which the invention is claimed (35 U.S.C. 120), (3) an earlier-filed, related "parent" application of a later-filed divisional application in which the invention is claimed, (4) an earlier-filed provisional application that establishes an earlier "priority date" for the later-filed application in which the invention is claimed or (5) an earlier-filed international (PCT) application that designates the U.S. (35 U.S.C. 363). A "first" filing is the first application to adequately describe a particular invention and to disclose "how to make" and "how to use" at least the best mode of the invention that also claims that invention (35 U.S.C. 112). A "parent" application is an earlier-filed, copending patent application of an inventor that describes and discloses a given invention.