Section 905.01 Classification Scheme for CPC

The CPC classification system arranges subject matter into hierarchical arrays.

  • (A) The highest array or level is the Section.
  • (B) Each section is subdivided into Classes.
  • (C) Each class is subdivided into one or more subclasses.
  • (D) Each subclass is broken down into Groups (main groups and subgroups).

Each part of this hierarchical structure is identified by classification symbols. Specifics about each element of the classification symbol are described below.

(A) Section Symbol – Each section is designated by one of the capital letters A through H and has an associated section title. There are nine sections, eight of which correlate to the sections of the International Patent Classification (IPC). The ninth section is used for classifying documents covering subject matter pertaining to a plurality of the sections. The table below shows the sections with their associated CPC and IPC section titles.

Letter Designation CPC Section IPC Section
A Human Necessities Human Necessities
B Performing Operations; Transporting Performing Operations; Transporting
C Chemistry; Metallurgy Chemistry; Metallurgy
D Textiles; Paper Textiles; Paper
E Fixed Construction Fixed Construction
F Mechanical Engineering; Lighting; Heating; Weapons; Blasting Engines or Pumps Mechanical Engineering; Lighting; Heating; Weapons; Blasting Engines or Pumps
G Physics Physics
H Electricity Electricity
Y General Tagging of New Technological Developments; General Tagging of Cross-over technologies spanning over several sections of the IPC; technical subjects covered by former USPC cross reference art collections and digest

(B) Class Symbol – Each class symbol consists of the section symbol followed by a 2 digit number (e.g., C07). Each class symbol is associated with a title.

(C) Subclass Symbol – Each subclass symbol consists of the class symbol followed by a letter (e.g., C07D). Each subclass symbol is associated with a title.

(D) Main Group Symbol – Each main group symbol consists of the subclass symbol followed by a one- to four- digit number, the oblique stroke, and the number 00 (e.g. C07D 203/00). Each main group number is associated with a main group title which precisely defines a field of subject matter within the scope of its subclass and a definition.

(E) Subgroup Symbol – Each subgroup symbol consists of the main group symbol, but the number “00” in the main group symbol is replaced with an alternative number of up to six digits (e.g. C07D 203/02). Each subgroup symbol is associated with a title and definition.


CPC Symbols C07D 203/00 or C07D 203/02

Example: CPC Symbols C07D 203/00 or C07D 203/02