MPEP § 906 — MPEP § 906
Current through: 2022-07-01

906-International Classification of Patents for Inventions 
 
 

 
 
 
 
 
 
 
 

 

 
 
 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

 
 
 
 
 

 
 
 
 
 
 
 
 
 
 
 

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 Chapter 0900 

 Section 906 
 

 
 
 
 
 
 906 International Classification of Patents for
 Inventions [R-07.2015]
 

 In accordance with the Strasbourg Agreement Concerning the
 International Patent Classification, the United States is required to indicate on its
 issuing documents the classification symbols of the International Patent Classification
 2006 (Eighth Edition), hereinafter referred to as “Int. Cl.”
 

 The complete Int. Cl. symbols must be placed in the indicated
 space on the Image File Wrapper (IFW) issue classification form when an application is
 issued.
 

 I. INT. Cl. LAYOUT The layout of the Int.Cl. is explained below with
 reference to the sample page.
 

 A. Section The Classification represents the whole body of
 knowledge which may be regarded as proper to the field of patents for invention,
 divided into eight sections.
 

(A)
 Section Symbol — Each section is designated by one
 of the capital letters A through H.
 

(B)
 Section Title — The section title is to be
 considered as a very broad indication of the contents of the section. The eight
 sections are entitled as follows:
 

 
 A. Human Necessities

 B. Performing Operations; Transporting

 C. Chemistry; Metallurgy

 D. Textiles; Paper

 E. Fixed Constructions

 F. Mechanical Engineering; Lighting; Heating;
 Weapons; Blasting
 

 G. Physics

 H. Electricity

 (C)
 Contents of Section — Each section title is
 followed by a summary of the titles of its main subdivisions.
 

(D)
 Subsection — Within sections, informative headings
 form subsections, which are titles without classification symbols.
 

 Example: Agriculture

 B. Class Each section is subdivided into classes.

(A)
 Class Symbol — Each class symbol consists of the
 section symbol followed by a two-digit number.
 

 Example: A 01

(B)
 Class Title — The class title gives an indication
 of the content of the class.
 

 Example: A 01 Agriculture; Forestry; Animal
 Husbandry; Hunting; Trapping; Fishing
 

 C. Subclass Each class comprises one or more subclasses.

(A)
 Subclass Symbol — Each subclass symbol consists of
 the class symbol followed by a capital letter.
 

 Example: A 01 B

(B)
 Subclass Title — The subclass title indicates as
 precisely as possible the content of the subclass.
 

 Example: A 01 B Soil Working in Agriculture or
 Forestry; Parts, Details, or Accessories of Agricultural Machines or Implements,
 in General
 

(C)
 Subclass Index — Some subclasses have an index which
 is merely an informative summary giving a broad survey of the content of the
 subclass.
 

 D. Group Each subclass is broken down into subdivisions referred
 to as “groups,” which are either main groups or subgroups.
 

(A)
 Group Symbol — Each group symbol consists of the
 subclass symbol followed by two numbers separated by an oblique stroke.
 

(B)
 Main Group Symbol — Each main group symbol consists
 of the subclass symbol followed by a one- to three-digit number, the oblique
 stroke, and the number 00.
 

 Example: A 01 B 1/00

(C)
 Main Group Title — The main group title defines a
 field of subject matter considered to be useful in searching for inventions.
 

 Example: A 01 B 1/00 Hand tools

(D)
 Subgroup Symbol — Subgroups form subdivisions under
 the main groups. Each subgroup symbol consists of the subclass symbol followed by
 the one- to three-digit number of its main group, the oblique stroke, and a number
 of at least two digits other than 00.
 

 Example: A 01 B 1/02

 Any third or fourth digit after the oblique stroke
 is to be read as a decimal subdivision of the second or third digit, respectively;
 e.g. 3/426 is to be read as “three slash forty-two point six”, not three slash
 four hundred and twenty six and is to be found after 3/42 and before 3/43, and
 5/1185 is to be read as “five slash eleven point eight five,” and is to be found
 after 5/118 and before 5/119.
 

(E)
 Subgroup Title — The subgroup title defines a field
 of subject matter within the scope of its main group considered to be useful in
 searching for inventions. The title is preceded by one or more dots indicating the
 hierarchical position of the subgroup, i.e., indicating that each subgroup forms a
 subdivision of the nearest group above it having one dot less. The subgroup title
 is often a complete expression, in which case it begins with a capital letter. A
 subgroup title begins with a lower case letter if it reads as a continuation of
 the title of the next higher, less-indented group, i.e., having one dot less. In
 all cases, the subgroup title must be read as being dependent upon, and restricted
 by, the title of the group under which it is indented.
 

 Examples

 A 01 B 1/00 1/24 Hand tools for treating meadows or
 lawns (The title of 1/24 is to be read as: 
 

 Hand tools for treating meadows or lawns.)

 A 01 B 1/00 1/16 Hand tools Tools for uprooting
 weeds (The title of 1/16 is a complete expression, but owing to its hierarchical
 position, the tools for uprooting weeds are restricted to hand tools.)
 

 E. Complete Classification Symbol A complete classification symbol comprises the combined
 symbols representing the section, class, subclass, and main group or subgroup.
 

 

 Guide Headings

 The main groups in each subclass are arranged in a
 sequence intended to assist the user. It has not, however, been found practicable to
 standardize the sequence. Where several successive main groups relate to common
 subject matter, it is usual to provide before the first of such main groups a “guide
 heading” which is underlined, indicating this subject matter (see, for example, the
 guide heading “Ploughs” before group A 01 B 3/00). The series of groups covered by
 such a heading extends to the next guide heading or to a line in heavy type extending
 across the column, which is used when the following group or groups relate to
 different subject matter for which no guide heading is provided. (See, for example,
 the line after A 01 B 75/00.)
 

 II. CLASSIFYING IN THE INT. Cl. SYSTEM 

 A. Selecting Subclasses Corresponding to U.S. Classes The effective scope of a subclass is defined by the
 following, taken together:
 

(A)
 The subclass title which describes, as precisely as
 is possible in a small number of words, the main characteristic of a portion of
 the whole body of knowledge covered by the Classification, this portion being the
 field of the subclass to which all its groups relate;
 

(B)
 Any references which follow the subclass title or
 the hierarchically higher class title. These references often indicate certain
 parts of the field described by the title which are covered by other subclasses
 and are, therefore, excluded. These parts may constitute a substantial part of the
 field described by the title and, thus, the references are in some respects as
 important as the title itself. For example, in subclass A 47 D — FURNITURE
 SPECIALLY ADAPTED FOR CHILDREN — a considerable part, namely school benches or
 desks, of the subject matter covered by the title is excluded in view of a
 reference to particular groups of subclass A 47 B, thus considerably altering the
 scope of subclass A 47 D;
 

(C)
 Any references which appear in groups or guide
 headings of a subclass and which refer subject matter to another class or subclass
 may also affect the scope of the subclass in question. For example, in subclass B
 43 K — INSTRUMENTS FOR WRITING; DRAWING-PENS — writing points for indicating or
 recording apparatus are referred out of group 1/00 to group 15/16 of subclass G 01
 D, thereby reducing the scope of the subject matter covered by the title of
 subclass B 43 K;
 

(D)
 Any notes or definitions appearing under the
 subclass title or its class, subsection, or section title. Such notes or
 definitions may define terms or expressions used in the title, or elsewhere, or
 clarify the relation between the subclass and other places. Examples are
 

 
 (1) Note (1) appearing under the title of the
 subsection “ENGINES OR PUMPS,” embracing classes F 01 to F 04, which notes
 define the terms used throughout the subsection,
 

 (2) the notes appearing under the title of
 subclass F 01 B, which define its scope in relation to subclasses F 01 C to
 F 01 P, and 
 

 (3) the note following the title of section C
 which defines groups of elements.
 

 B. Selecting Main Groups Corresponding to U.S. Mainline Subclasses The scope of a main group is to be interpreted only
 within the effective scope of its subclass (as indicated above). Subject to this, the
 effective scope of a main group is determined by its title as modified by any
 relevant references or notes associated with the main group or with any guide heading
 covering it. For example, a group for “bearings” in a subclass whose title is limited
 to a particular apparatus must be read as covering only features of bearings peculiar
 to that apparatus, e.g., the arrangement of bearings in the apparatus. Guide headings
 are intended to be only informative and, as a rule, do not modify the scope of the
 groups covered by them, except where it is, otherwise, clear from the context. By
 contrast, references in the guide headings modify the scope of the associated
 groups.
 

 C. Selecting Subgroups Corresponding to U.S. Indented Subclasses The scope of a subgroup is likewise to be interpreted
 only within the effective scope of its main group and of any subgroup under which it
 is indented. Subject to this, the scope of a subgroup is determined by its title as
 modified by any relevant references or notes associated therewith.
 

 See volume 9 of the International Patent
 Classification, entitled “Guide, Survey of Classes and Summary of Main Groups” for
 detailed procedures for classifying into and searching Int. Cl.
 

 
 III. U.S. INT. Cl. CONCORDANCE The Office of Patent Classification has prepared a revised
 Concordance between the U.S. classes and subclasses and the Int. Cl. In many areas, the
 two systems are conceptually different. With this in mind, it will be seen that a
 complete one-to-one correspondence between the two systems cannot be attained. An
 indication in the Concordance may refer to only one relevant group and not necessarily
 the only group in which the patent can or should be classified. For some inventions, the
 Concordance may not indicate any truly relevant group. Accordingly, the Concordance must
 be recognized as a guide to be used in conjunction with the Int. Cl., and not as a
 translation list.
 

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 901-Prior Art 
 901.01-Canceled Matter in U.S. Patent Files 
 901.01(a)-Ordering of Patented and Abandoned Provisional and Nonprovisional Application Files 

 
 

 901.02-Abandoned Applications 

 901.03-Pending Applications 

 901.04-U.S. Patents 
 901.04(a)-Kind Codes 

 
 

 901.05-Foreign Patent Documents 
 901.05(a)-Citation Data 

 901.05(b)-Other Significant Data 

 901.05(c)-Obtaining Copies 

 901.05(d)-Translation 

 
 

 901.06-Nonpatent Publications 
 901.06(a)-Scientific and Technical Information Center (STIC) 

 901.06(b)-Borrowed Publications 

 901.06(c)-Alien Property Custodian Publications 

 901.06(d)-Abstracts, Abbreviatures, and Defensive Publications 

 
 

 901.07-Patent Family Information 

 901.08-Global Dossier Public Access 

 
 

 902-Search Tools and Classification Information 
 902.01-Classification Manual for the U.S. Patent Classification System 
 902.01(a)-Index to the U.S. Patent Classification System 

 
 

 902.02-Class and Subclass Definitions in USPC 
 902.02(a)-Definition Notes in USPC 

 902.02(b)-[Reserved] 

 
 

 902.03-Classification Information 
 902.03(a)-Patent Classification Home Page on the Internet 

 902.03(b)-Patent Classification Home Page on the USPTO Intranet 

 902.03(c)-[Reserved] 

 902.03(d)-[Reserved] 

 902.03(e)-Automated Search Tools: PE2E SEARCH 

 
 

 
 

 903-Classification in USPC 
 903.01-Statutory Authority 

 903.02-Basis and Principles of Classification in USPC 
 903.02(a)-[Reserved] 

 903.02(b)-Scope of a Class in the USPC 

 
 

 903.03-Availability of Foreign Patents 

 903.04-Classifying Applications for Publication as a Plant Patent Application Publication in USPC 

 903.05-Addition, Deletion, or Transfer of U.S. Design Patents by USPC Classification 

 903.06-Harmonized Subclasses 

 903.07-Classifying and Cross-Referencing Design and Plant Applications at Allowance 
 903.07(a)-Cross-Referencing Design and Plant Applications — Keep Systematic Notes During Prosecution 

 
 

 903.08-[Reserved] 
 903.08(a)-[Reserved] 

 903.08(b)-[Reserved] 

 903.08(c)-[Reserved] 

 903.08(d)-[Reserved] 

 903.08(e)-[Reserved] 

 
 

 903.09-[Reserved] 
 903.09(a)-[Reserved] 

 
 

 
 

 904-How to Search 
 904.01-Analysis of Claims 
 904.01(a)-Variant Embodiments Within Scope of Claim 

 904.01(b)-Equivalents 

 904.01(c)-Analogous Arts 

 
 

 904.02-General Search Guidelines 
 904.02(a)-Classified Search 

 904.02(b)-Search Tool Selection 

 904.02(c)-Internet Searching 

 
 

 904.03-Conducting the Search 

 904.04-Search of Related Post-Grant Proceedings 

 
 

 905-Cooperative Patent Classification 
 905.01-Classification Scheme for CPC 
 905.01(a)-CPC Titles 
 905.01(a)(1)-References within CPC Titles 

 905.01(a)(2)-Notes Found in CPC schemes 

 905.01(a)(3)-Warnings Found in CPC schemes 

 905.01(a)(4)-Guidance Headings Found in CPC Schemes 

 
 

 
 

 905.02-CPC Definitions 

 905.03-Classifying in CPC 
 905.03(a)-The CPC Database 

 905.03(b)-Approach to classification in CPC 

 905.03(c)-Combination Sets 

 
 

 
 

 906-International Classification of Patents for Inventions 

 907-Locarno Classification Designations 

 908-[Reserved] 

 909-Routing and Docketing of Applications 
 909.01-Assignment, Transfer and Classification Challenges under Cooperative Patent Classification (CPC) 
 909.01(a)-New Applications in CPC 

 909.01(b)-Classification and Assignment to Examiner in CPC 

 909.01(c)-Immediate Inspection of Amendments 

 909.01(d)-Classification Challenge Procedure in CPC 

 
 

 909.02-Applications: Assignment and Transfer in USPC 
 909.02(a)-New Design and Plant Patent Applications under 35 U.S.C. 161 

 909.02(b)-Classification and Assignment to Examiner 

 909.02(c)-Reserved 

 909.02(d)-Transfer Procedure 

 909.02(e)-General Guidelines Governing the Assignment of Nonprovisional Design and Plant Applications for Examination 

 
 

 
 

 

 

 
 

 
 
 

 
 

 

 
 
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 Last Modified: 
 
 03/09/2026 20:49:44