Another special claim form is a functional claim. Functional claims include a clause that defines one or more elements by function, rather than structure.

Another special claim form is afunctional claim. Functional claims include a clause that defines one or more elements by function, rather than structure. Such clauses include “means-plus-function” clauses or “step-plus-function” clauses.

A “means” clause or “step” clause defines an element or feature in a product or a method claim by what it does (function) rather than by what it is (structure).

Use of a means-plus-function clause is governed by 35 U.S.C. § 112, paragraph 6. The statute does not allow a claim solely directed to a single means-plus-function clause. Means-plus-function language incorporates two different sets of structures into the elements and limitations of the claim: the embodiment disclosed in the specification and all equivalents of that embodiment. The structures are incorporated during examination and during infringement analysis after a patent is granted. Means-plus-function language is helpful when a patent includes several embodiments or to vary the scope of claims within the application.

A final special claim type is anomnibus claim. In the United States, omnibus claims are not applicable to utility patents. They are, however, used in design patents and plant patents. Some foreign countries allow the use of omnibus claims. The form of an omnibus claim is very simple. The claim simply states “ a device substantially as shown and described.”