Understanding Types of Classifications in Patent Search


Classifications in patent search is a system for patent office examiners or other people to code documents. For example, patent applications published according to the technical features of their content.

Patent classification systems were originally developed for sorting paper documents. But, nowadays, you may use them to search patent databases as well.

In addition to that, an agreement among people fixes a patent classification.

Moreover, you may ease the search process by understanding types of classifications in patent search. It is so because, you may search most of the documents in patent databases on the basis of the classification system.

Classifications in Patent Search

There are 3 basis for the Patent Search classification:

  • Jurisdiction.
  • Document type.
  • Subject matter. 

Based on Jurisdiction

International Patent Classification (IPC) 

There is a global acceptance for The International Patent Classification or IPC.

United States Patent Classification (USPC)

The United States Patent and Trademark Office (USPTO) fixes the United States Patent Classification or USPC  .

Derwent Classification System

An enterprise fixes The Derwent Classification System.

Cooperative Patent Classification (CPC) 

The United States Patent Office (USPTO) and the European Patent Office (EPO) launched a joint patent classification system called CPC.

German Patent classification (DPK) 

The German Patent Office (Deutsches Patentamt) fixex The German Patent Classification (DPK).

Based on document type

Original Classifications (OR) 

All U.S. patents have one and only one important classification known as an OR classification.

The OR classification is in a primary subclass. Moreover, the OR classification’s class is the same as the class of the controlling claim in the patent. And, it can also be the same as the most superior class of the controlling claim if it has more than one classification.

Moreover, the subclass of the OR classification is determined by the classification of whichever claim is classified deepest in the highest subclass array in the class. Classification in patent search

Cross Reference Classifications (XR) 

You nay classify any document in the USPC in more than one subclass. However,you cannot classify any document more than once in the same subclass.

 All classifications other than the OR classification are referred to as cross-reference (XR) classifications. This is only if a U.S. patent has more than one classification.

Subsequently, keep an XR classification of a U.S. patent  in any subclass except a foreign (FOR) subclass.

XR classifications based on the claimed and/or unclaimed invention in the patent are mandatory classifications.

Primary Classifications (PR)

U.S. PGPub documents classified in the USPC are assigned one and only one principal mandatory classification. Thus, this classification is known as the Primary Classification or PR.

You must keep the PR classification of a U.S. PGPub document in a primary subclass. In addition, the PR classification is suggestive of the invention as a whole or the main inventive concept using the claims as a guide.

Hence, the experience and knowledge of the state-of-the-art is one of the factor in how these documents are classified. 

Secondary Classifications (SR)

Classifications in addition to the PR on a U.S. PGPub document are known as Secondary Classifications or SR. All invention information subject matter in a U. S. PGPub document should receive a mandatory classification.

Moreover, any informtion disclosure in a U.S. PGPub separately classifiable apart from the PR is assigned a mandatory SR classification. Also, Other non-invention information thought to have particularly good search value is assigned a discretionary SR classification. The person classifying the documents does this.

Based on Subject Matter

Design classes

 Design patents, issued under Title 35 of the United States Code in Section 171 (35 U.S.C. 171), protect ornamental designs. The principal classification, i.e., OR classification, for a design patent is in one of the design classes. Also, you may easily recognize the design patents by their patent number. It usually begins with the letter “D.” The USPC currently has 33 design classes.

Plant class

Plant patents, issued under 35 U.S.C. 161, protect new and distinct varieties of asexually reproducible plants. The USPC has one designated PLT plant class to classify all plant patents. Also, Plant patents are the only US patents with full color drawings.

Utility classes

Utility patents protect any new and useful process, machine, manufacture, or composition of matter, or any new and useful improvement thereof. The Utility classes have a class number from 1 to 999. The USPC currently has more than 400 utility classes.

Also, some utility classes are exclusively for a single statutory category. Examples of such categories include articles of manufacture, processes, and machines to make articles of manufacture, in addition to composition and compound classes. Classification in patent search

Thus, it is a prudent step to understand the types of classifications in patent search. Also, it helps to conduct a thorough and full patent search with minimum amount of inputs.

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