Examiner's Handbook Chapter Four - Determination of a Class for Original Classification or Assignment for Examination

When the content of each claim has been analyzed, it may be found that the patent or application includes two or more claims that are drawn to diverse subject matter (i.e., they are classifiable in different classes).

For search and retrieval purposes, merely placing the document in each class would suffice. However, for both administrative and legal purposes within the USPTO (e.g., ensuring the examination of patent applications by the best qualified examiner on the subject matter, restricting patent applications to properly related inventions, interference or infringement searches, etc.), there is a need to designate for U.S. patents a primary, or Original, classification. All other classifications are designated as cross-references, and the corresponding patent documents are so labeled or stamped at the top of the cover page. The following selections relate to the basis on which the "original" class is chosen or how applications having multiple claimed inventions are assigned.

A. Original Placement Between Classes

The process for selecting the claimed invention that will control original classification or assignment designation is effected by considering in turn the factors listed below:

  • Selection of the most comprehensive claim;
  • Selection among categories of subject matter when claims are of equal comprehensiveness, or when the most comprehensive claim cannot be determined;
  • Selection among superiority of types of subject matter;
  • Selection among generic classes and species classes thereunder; and
  • Selection among classes in "related subject" listing.

1. Selection of the Most Comprehensive Claim

The claimed disclosure setting forth the most comprehensive organization (for example, a claim to a combination as compared to a claim to a subcombination or element of that combination) will control placement of a patent or application among classes. This is illustrated by comparing the following two claims (which not only differ in comprehensiveness, but also are directed to different categories of subject matter) each of which define subject matter properly classified in a different class:

Claim 1

A laminated sheet comprising two panels of aluminum bonded with an intermediate layer of a binder, said binder comprising an elastic, self-vulcanizing rubber-like cement, the adjacent faces of the panels being roughened in a cross-hatched pattern to facilitate adhesion of the cement, two opposite edges of the sheet being notched with corresponding, interfitting dovetail cutout portions to facilitate securing the edges one to the other.

Claim 2

A process comprising scoring the faces of two aluminum panels in a cross-hatched pattern, applying a binder to the scored faces, pressing the coated faces together to secure the panels and forming a sandwich and then bending the sandwich and securing the opposite edges to each other to form a tube.


Claim 1 encompasses a product comprising a laminated sheet. Claim 2 encompasses a process of making such a sheet, but includes the additional steps of bending the sheet and securing the edges to form a tube. Process Claim 2 thus contains a greater extent of subject matter than does Claim 1 and is therefore more comprehensive. Assuming that separate classes provided for the subject matter in Claim 1 and 2, respectively, a patent with these two claims should be placed as an original in the class providing for the subject matter of Claim 2.

Please note that mere details of a subcombination, as a rule, do not generally increase the comprehensiveness of a claim. Thus, Claim 1 above would not become more comprehensive than Claim 2 if Claim 1 were amended merely to recite the details of the nature of the binder composition.

2. Selection Among Categories of Subject Matter

When a patent includes separate claims to two or more different categories of subject matter and none of the claims is more comprehensive than the other(s) or if greater comprehensive-ness cannot be determined, the Original is placed in the class providing for the claimed category that appears highest in the following list:

(1) Process (of using product 2, e.g., using a fuel or radio trans­mitter)
(2) Product (of manufacture, e.g., a fuel or radio transmitter)
(3) Process (of making product 2)
(4) Apparatus (to perform 3 or to make 2, e.g., machine, tool, etc.)
(5) Materials (used in 3 to make 2)

For example, when considering claims to a radio trans­mitter (category 2) and to a process of manufacturing the same (category 3), the claim to the transmitter would control class assign­ment. Similarly, a claim to a process of using the transmitter (category 1) would control over a claim to the transmitter or process of making it.

Modern patent classification schedules often separate categories of related subject matter into different classes or, if several categories are included in the same class, put them in different groups of subclasses. In the latter case, the priority given above is frequently used to determine order of subclass groupings. For situations where all claims are provided for in the same class, see Section V, B, below, to determine placement in the proper subclass.

3. Selection Among Superiority of Types of Subject Matter

When placement of the Original cannot be determined from considerations of (a) comprehensiveness or (b) categories of subject matter, placement is next determined by considering the highest category below that provides for claimed subject matter.

(1) Relating to maintenance or preservation of life

(2) Chemical subject matter

(3) Electrical subject matter

(4) Mechanical subject matter

(a) Dynamic (relates to moving things or combinations of relatively moving parts)

(b) Static (stationary things or parts nonmoveably related)

4. Selection Among Generic Classes and Species Classes Thereunder

When placement of the Original cannot be determined from (a) comprehensiveness, (b) categories of subject matter, or (c) types of subject matter, placement is next determined by considering whether the claims fall into classes having a genus-species relationship to each other. An example of such a situation is as follows: Class 427 is regarded as the generic coating class, while Classes 204, 205, and 148 provide for specific types of coating and are regarded (at least in part) as species coating classes.

5. Selection Among Classes in "Related Subject" Listing (Last Resort Only)

The number of a class generally has no significance insofar as superiority of one class relative to another. The class number is merely an arbitrary mark of identification. Nor is the class listing in the "Classes Arranged in Alphabetical Order" an order of superiority. The title of a class is an accident of language and varies from one language to another.

However, an organization of the applied sciences into four major areas called Classes Within the U.S. Classification System Arranged by Related Subject Matter (CABRSM) is a theoretical organization of all the classes into four major groups. Within each of the areas the classes have been listed in a hierarchy suggesting an order of superiority. The USPC system provides for the storage and retrieval of every patent document that a patent examiner needs to review when examining patent applications. Therefore, in the aggregate, the system must be exhaustive of all patentable subject matter under patent laws. Although the system is primarily designed to assist patent examiners performing patentability searches, the system is used by a wide variety of other users ¾ e.g., patent attorneys and agents, people involved in research and development, and the patrons of the Patent and Trademark Depository Library (PTDL) system.

Some class positions in the listing show superiority very well, whereas others show it less or not at all. Notwithstanding, as a last resort, where the other bases for selection discussed above cannot be applied, a controlling claim is sometimes selected according to this listing. The controlling claim is identified as the one having subject matter provided for by the class that appears highest in such listings.

6. Exceptions

(a) Where special agreements between Groups are in effect, such as for high-temperature superconductivity applications and for certain biotechnology areas, these agreements override all other considerations.

(b) Where the historical placement of patents having particular claimed disclosure has been contrary to written definitions and notes, the historical placement overrides all other considerations, except the special agreements mentioned above, and controls placement of like subject matter until corrective reclassification is effected.

(c) Classification definitions (particularly the search notes and lines with other classes) must be read for possible excep­tions to the selection procedures discussed in 1-5 above, inasmuch as disclosures in a given area of technology may have required deviation from these procedures. Any deviation will be mentioned, and explained, in a modern class definition.

The procedures outlined above presume that the person reviewing the claims knows the class in which each claimed invention is classified. The following Section offers suggestions on how to determine which classifica­tion is most appropriate for any claimed invention where the class is not known.

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