Concordance Between the U.S. Patent Classification System (USPC)
and
the International Patent Classification (IPC) Seventh Edition
-------------------------

Classifying Within The
International Patent Classification System (IPC)

What Subject Matter to Classify

The first step when classifying patent documents into the IPC, is to determine what are the essential characteristics of the novel technical subject matter claimed (i.e., the invention). For US Examiners, this is always the subject matter that is found in the claimed disclosure and covered by the original and essential cross-reference classifications assigned to the document in the US Patent Classification system (USPC). The invention should be classified as a whole, when possible, and not merely by one of its constituent steps or components.

Locating Potential Groups

In many instances examiners can quickly locate an appropriate IPC⁷ classification for their document by using our Concordance. Often, one of the IPC⁷ classifications listed for a particular US original or a cross-reference subclass in the Concordance either (a) is the correct IPC⁷ group or (b) includes another group located within the suggested group's IPC subclass schedule appropriate for the document being classified.

In the instances where the IPC⁷ classifications indicated in our Concordance do not seem to be appropriate, the user should consult the IPC⁷ "Official Catchword Index" for additional help. With the assistance of the IPC⁷ Official Catchword Index, the examiner should be able to locate at least some possible IPC classifications. The examiner should carefully search the Index for both (a) specific terms and general terms for the claimed subject matter as a whole and (b) terms used for significant steps or components, per se, of the claimed subject matter.

Alternatively, examiners can quickly scan the Survey of Classes and the summary of IPC⁷ main groups in Volume 9 of the IPC⁷ manuals to locate possible IPC⁷ classifications.

Choosing and Assigning Proper Classification

The IPC system also hierarchically indents dependent titles and the titles are intended to be read in a manner similar to indented USPC titles. However, the IPC system does not have a single standard superiority rule similar to that of the USPC system (i.e., the first occurring subclass of two coordinate subclasses in a Class is always superior). The IPC system instead utilizes either:

1. general placement rules for superiority when no rules are stated in the notes or text of a IPC subclass’ schedule or its Class, or
2. one or more of several particular placement rules that are clearly stated in the notes or text of an IPC subclass’ schedule or its Class (e.g., last-place rule - where the last occurring appropriate main group is superior).

When a particular classification rule is stated for classifying inventions within the groups of an IPC subclass, that particular rule is applicable and the general classification rules are overridden. Therefore, it is critical for examiners to first read all the titles, explanatory notes, and references at every level of classification prior to assignment. These rules significantly affect the proper placement of patent documents and can determine superiority between coordinate groups within an IPC subclass’ schedule.

Examiners should also remember that the subject matter proper for each group is restricted by all limitations to its scope imposed by the title of its IPC subclass, all higher level group titles under which it is indented, its own title, and relevant notes and references. The only exception, is that IPC subclass or group titles that specify only a process, a product, or an apparatus category of invention may also include another category within their scope for its specific subject matter (e.g., a group for "hats" could also take "making hats"). This exemption is utilized only when the other related category of invention is not provided for elsewhere in the IPC.

The first general rule for classifying an invention is that the same invention should be assigned only to the Class, IPC subclass, and group title the invention best fits, even in situations where there are plural group titles which it could fit. An exception to this general placement rule is followed when the novel subject matter in the claims are limited to a single step or component of a combination (e.g., a claim to an old combination) which is useful with processes, products, or apparatus, other than that claimed in combination therewith. The novel step or component must then additionally be classified into a group providing only for the novel subcombination.

A second general classification rule is used when a patent document includes a particular invention fitting both a general utility IPC subclass (i.e., one encompassing a range of divergent, specific utility concepts which either share an important common distinguishing characteristic or solve similar problems - called "function-oriented" in the IPC) and a specific utility IPC subclass (i.e., one specially adapted or limited to a use - called "application-oriented" in the IPC). In this situation, the examiner must determine if the claimed subject matter (a) is specially adapted or limited to the specific purpose or (b) has a more general use not fully encompassed by the specific utility IPC subclass. If there is no meaningful claimed disclosure to at least one additional use classifiable in another IPC subclass, then the patent document should be classified only under the specific utility IPC subclass. Otherwise, the general utility IPC subclass, if it fully covers all claimed uses, will take precedence over any specific utility IPC subclass for assignment. However, if a particular utility is considered important, the examiner should also classify the patent document therein, since the ultimate aim is for successful retrieval of the information. In cases where no general utility IPC subclass exists which covers all claimed uses and the claims are not limited to one specific utility under a single IPC subclass, the patent document should be classified in all the most appropriate specific utility IPC subclasses. If a copy of the patent document is believed to be useful in a general utility area covering some of the claimed uses, it may also be classified there.

The last general classification rule is applied when a patent document claims diverse technical inventions covered by either (a) two or more coordinate subgroups under a single main group or (b) plural main groups. It is that the patent document should be classified into each appropriate group. An exception to this general rule is when novelty resides solely in the combination or interrelationship of the diverse technical inventions found in each of the independent groups (e.g., manufacturing process having sequential steps, apparatus having distinct cooperating components). When this occurs, and no group specifically provides for this combination of inventions, then the claims are classified in the following manner:

1. within a main group, into the furthest indented hierarchical group having all the pertinent groups indented thereunder which provide for the individual steps or components;
2. if the pertinent groups are not indented under a common main group, then classification is within the main group in the IPC subclass schedule providing for combinations of subject matter from different main groups; or
3. if no such combination main group exists, then classification is into all of the most appropriate groups providing for at least one of the novel individual steps or components of the invention.

Inquiries relating to the content of this web report may be directed to:

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