IPC - International Patent Classification
Classification Practice
- What and Where to Classify (and Search)?
IPC Section, World Intellectual Property Organization (WIPO)
October 2014
Where?
Selecting appropriate places is similar for
 Classifying patent applications / granted patents;
 Searching state of the art for examination.
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What is classified?
Two types of technical information worth classifying:
 Invention information
Technical information worth granting a patent
 obligatory classification
 Additional information
Supplementary non-invention information
the classifier/examiner considers important
 discretionary classification
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Invention Information
 Technical information that represents an addition to the
state of the art
 All novel and unobvious subject matter specifically
disclosed in a patent document
 Claims as guidance, but also in description
 In examined patent only in claims
 Each piece of invention information classified separately
 At least one symbol given as Invention Information even
if no invention
 obligatory classification
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Invention Information
 Technical subject with which an invention is
essentially concerned should be classified as a whole
– not by separate classification of constituent parts
unless constituent parts are novel and unobvious.
 When classifying a large system as a whole, parts or
details should also be classified if inventive.
Example: a leaf spring into a vehicle wheel suspension
- classified in the place for this system (B60G vehicle
suspension arrangements), and if the leaf spring as such is
novel and unobvious, also classified in the place for the thing
itself (F16F springs)
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Additional information
 Non-trivial technical information which does not represent
an addition to the state of the art but might constitute
useful information for search.
 Complementing invention information, e.g.
 elements or components of a process or structure;
 constituents of a composition or mixture;
 use or applications of classified technical subjects if
non-inventive.
 Allows search by combination of symbols.
 non-obligatory classification
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Invention and Additional Information
Example:
Metal rod wine rack (Training Example:M5)
Invention Information
A wine rack which is easily dismantled
Additional Information
A rigid wine rack made of “wire”
Int. Cl.
A47B 73/00 (2006.01) Bottle cupboards; Bottle racks
A47B 47/02 (2006.01) Racks characterised by features related to dismountability
A47B 55/02 (2006.01) Racks having essential features of rigid construction (made of wire)
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1st step of classifying (search)
Determine the subject matter to be classified (searched).
Basic categories of subject matter:
 Processes, products, apparatus or material
 Things “per se” and adaptations
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Categories of Technical subjects
Categories used in IPC:
 Processes: e.g. preparation of foodstuffs, testing,
methods of operating machines, processing of
information, separation, etc.
 Products: e.g. chemical compounds, compositions,
fabrics, articles of manufacture, etc.
 Apparatus: e.g. tools, machines, devices, etc.
 Material: ingredients of mixtures, etc.
 Methods: of using a product or performing an operation
 Each category should be separately classified if needed.
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Categories of Technical subjects
 For example, if a product is inventive and its method of
manufacture is inventive,
then both the product and its method of manufacture
should be classified.
 In addition, if a particular use is disclosed, then the use
should also be classified.
 Numbers of classification do not always correspond to
independent claim.
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Categories not explicitly provided for
in classification titles
 If for one of the categories, no distinct place has been
identified by the titles of the IPC, the most appropriate place
existing for the other categories is used for classifying:
 Chemical compounds, and a specific field of use;
 Chemical mixtures or compositions, or its use or application;
 Preparation or treatment of compounds, or the Compound;
 Apparatus or Processes.
 Definitions, notes, references may provide specific
information.
 See § 92-100 of the Guide to the IPC.
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Function and application-oriented places
 IPC discriminates between two fundamental categories of
technical subjects:
• Things “per se”, “in general”, i.e. characterised
by their intrinsic nature or function,
i.e. independent of its field of use;
► Function-oriented place
• Things specially adapted for particular use
or purpose.
► Application-oriented place
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Function and application: examples
Function-oriented Places
- C07: Organic compounds characterised by structure only
- F16K (Valves), B01D (Filters), F16F (Springs)
Application Places
- C05 covers use of organic compounds as fertilisers
- A61F 2/24 covers mechanical valves specially adapted
for insertion into a human heart
- A47J 31/06 covers filters for coffee or tea makers
- B60G 11/00 covers incorporation of a spring into
the suspension of a vehicle
“specially adapted for” in the title
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What and Where ?
N.B. One document may contain several different
technical subject matters (inventive things) to be
classified (e.g. independent claims).

All inventive things have to be classified, several
classifications must be assigned if needed!
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Example
Patent documents
IPC symbols
Claim 1
- Claim 2 (dependent claim)
- Claim 3 (dependent claim)
G67K 1/00 (invention information)
• Claim 4
- Claim 5 (dependent claim)
F88Z 1/00 (invention information)
B91M 1/00 (additional information)
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Where?
 Traditional principle:
As few symbols as possible, as much as necessary!
> Idealy one symbol
(historically important reason: limit paper search file)
 Complementary principle:
Classify everything interesting for search purposes!
(efficient retrieval of documents)
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Types of IPC symbols
 Classification symbols normally stand for concepts
(longer titles), i.e. a combination of
characteristics/features.
 Indexing codes only describe one additional
characteristic of the subject matter to be classified
 i.e. adding an indexing symbols is like adding a
keyword (indexing).
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Indexing Codes
 Used only in specific areas to classify additional information
of interest for search
 Discretionary classification
 i.e. indexing codes are never given alone, they always
supplement one or several ordinary symbols.
 Never presented first
 Only specific places are used for indexing codes:
 Indexing subclasses (B29K, B29L, C10N, C12R, F21W,
F21Y)
 Indexing main groups (e.g. A01D 101/00, C04B 103/00,..)
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Example of Indexing subclasses: F21W
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Example of Indexing scheme: C04B 103/00
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Types of IPC Symbols
Summary
 Invention information:
 Classification symbols
 Additional information:
 Classification symbols
 Indexing codes
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Classification Rules
Different classification rules may apply:
First place priority rule
Last place priority rule
B32B
Note(s)
5. In groups B32B 1/00-B32B 33/00, the first place priority rule is
applied, i.e. at each hierarchical level, in the absence of an indication
to the contrary, classification is made in the first appropriate place.
Note(s)
In this subclass / main group(s) / group(s), the last place priority
rule is applied, i.e. at each hierarchical level, in the absence of an
indication to the contrary, classification is made in the last
appropriate place.
 give priority between groups of the same hierarchical level
 avoid multiple classification in case of overlap
Special rules (see§155 of the Guide)
Multiple classification (C04B 38/00)
Subject-specific rules (C08L)
Common rule (default, if no other rules specified)
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Common Rule
 Common Rule aims at limiting multiple classification when
many symbols should be allotted.
 Priority for
 groups for more complex subject matter
 groups for more specialised subject matter
 However, classification in several places if
 priority not given, only places for subcombinations
 place of lower priority is useful for search
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Question
Example:
Inventive subject matter A (1/00) is characterized by subcombinations of
B (1/04) and C (1/08) in the following scheme which has no provision for
combinations:
1/00
1/02
1/04
1/06
1/08
main group A
. subgroup
. subgroup B
. subgroup
. subgroup C
Question: Classification(s) under CR/FPPR/LPPR?
Answer:
if Common Rule > B and C
if First Place Priority Rule > B
if Last Place Priority Rule > C
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Question
Q. In main group A21D 2/00, where would you classify
treatment of dough by adding a mixture of ascorbic acid
and seed germs? (In view of the last place priority rule in
group A21D 2/00.)
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A21D 2/00 Treatment of flour or dough by adding materials thereto
before or during baking (A21D10/00 takes precedence)
Note(s) In groups A21D 2/02-A21D 2/40, the last place priority rule is applied,
i.e. at each hierarchical level, in the absence of an indication to the
contrary, a substance is classified in the last appropriate place.
A21D 2/02 · by adding inorganic substances
A21D 2/04 · · Oxygen; Oxygen-generating compounds, e.g. ozone, peroxides
A21D 2/06 · · Reducing agents
A21D 2/08 · by adding organic substances
A21D 2/10 · · Hydrocarbons
A21D 2/12 · · Halohydrocarbons
A21D 2/14 · · Organic oxygen compounds
A21D 2/16 · · · Fatty acid esters
A21D 2/18 · · · Carbohydrates
A21D 2/20 · · · Peroxides
A21D 2/22 · · · Ascorbic acid
A21D 2/24 · · Organic nitrogen compounds
A21D 2/26 · · · Proteins
A21D 2/28 · · Organic sulfur compounds
A21D 2/30 · · Organic phosphorus compounds
A21D 2/32 · · · Phosphatides
A21D 2/34 · · Animal material
A21D 2/36 · · Vegetable material
A21D 2/38 · · · Seed germs; Germinated cereals; Extracts thereof
A21D 2/40 · Apparatus for the chemical treatment of flour or dough
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Selecting / Finding IPC place
 Different approaches/strategies:
 Browsing the IPC scheme
 Catchword Index
 Terms (text search of the IPC)
 IPCCAT (automated classification tool)
 STATS (statistical approach using PATENTSCOPE)
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Browsing the IPC scheme
Simple approach:
Section
Browsing the IPC
Unspecific titles
Class
Subclass
Main Group
Specific titles
Subgroups
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Catchword Index
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Catchword Index
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Terms (text search in the IPC)
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IPCCAT (categorization tool)
 A categorization assistance tool for the IPC designed to
help to classify patent documents at IPC subclass/main
group level
 Designed with the concept of full phrases describing the
technical subject matter (not a keyword search tool)
 Upload of document is possible
 Based on artificial neural network
 It is suggested that patent abstracts be used (at the
minimum), and not a random selection of text from the
patent description.
 Need to consult the IPC scheme
 Available at: https://www3.wipo.int/ipccat/
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IPCCAT
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IPCCAT
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IPCCAT
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STATS (Statistical approach)
 Identifies IPC entries most frequently referenced
in the PATENTSCOPE database searched by
particular terms.
 Statistical presentation of the search results is
performed according to IPC subclasses and
groups.
 Search by simple terms and multi-term
(combination of simple terms separated by a
space) in all patent collections of the
PATENTSCOPE.
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STATS
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STATS
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STATS
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STATS
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