The U.S. Patent Classification System is a static system and is no longer updated for the utility classes. The USPC remains active for the plant and design classes.

The United States Patent Office (the Office) maintains an electronic classification manual for the U.S. Patent Classification System (USPC). The complete manual is available to USPTO personnel from the Classification Home Page (https://ptoweb.uspto.gov/patents/classification-resources/ ), which is accessible from the desktop via the Patent Examiner’s Toolkit. The Manual of Classification is also available via the Internet at www.uspto.gov/SearchClassification, however The Manual of Classification will no longer be updated after December 31, 2014. See MPEP § 905 et seq. for information regarding the Cooperative Patent Classification System.

Each class has a title descriptive of its subject matter, is identified by a class number, and is subdivided into a number of subclasses. Each subclass also has a descriptive title, is identified by a subclass number, and the subclass number is an integral number that may contain a decimal portion and/or alpha characters. A complete identification of a subclass requires both the class and subclass number and any alpha or decimal designations; e.g., 417/161.1A identifies Class 417, Subclass 161.1A.

The Manual of Classification for the USPC system contains ordered arrangements of all class and subclass titles, the ordered arrangements are referred to as class schedules. The class and subclass titles are brief and are as suggestive as possible of the subject matter included. Therefore, it is best not to depend exclusively upon titles to explain the subject matter encompassed by a class and subclass but to refer also to the respective definitions and notes. If a search is to be expeditious, accurate, and complete, the Manual of Classification should be used only as a key to the class or subclass definition and appended notes.

The Manual of Classification for the USPC system has the following parts:

1. (A) Overview of the U.S. Patent Classification System.
2. (B) Classes Within the U.S. Classification System Arranged by Related Subject Matter: A hierarchical arrangement of class titles organized into four main groups by related subject matter. Only as a last resort should this hierarchical arrangement of class titles, be used to determine document placement, i.e., when none of the other classification criteria, such as comprehensiveness, etc., allow placement. This part also includes an exact hierarchical listing of the synthetic resin and chemical compound classes.
3. (C) Classes Arranged by Art Unit (CAAU): A list, in numerical order, by art unit indicating the classification(s) assigned to each.
4. (D) Classes Arranged Numerically With Art Unit and Search Room Locations (CAN): A list of classifications in numerical order by class number giving the class title, the art unit to which the art is assigned, and the examiner search room in which the art can be found.
5. (E) Classes Arranged in Alphabetical Order (CAA): A list of classes in alphabetical order by class title with associated class numbers.
6. (F) Class Schedules: Class schedules for utility patent, design, and plant classes.

The Index to the U.S. Patent Classification System (USPC) is an alphabetic listing of technical and common terms referring to specific classes and subclasses of the USPC. The index is used as an initial entry into the system and should not be considered exhaustive. All appropriate class schedules should be scanned for specifically related subclasses, and the definitions and associated notes of the pertinent classifications should also be reviewed, even when the citation found in the Index appears to be restricted to a specific subject matter area.

The Index is regularly updated. Suggestions or changes to the Index are encouraged and should be directed to the Technology Center (TC) classification contact in the TCs.

The Index is available online to USPTO personnel from the Classification Home Page – USPC Index. The Classification Home Page (http://ptoweb:8081/ ) is accessible from the desktop via the Patent Examiner’s Toolkit.