How to Find Classification Symbols for a Search

Date Published

Finding CPC/IPC symbols should be a usual part of a preliminary search. There are multiple strategies to find relevant classification symbols. In this section, the most common approaches, pragmatic and statistical approach, are presented with illustrated examples based on the CPC system.

The pragmatic approach involves finding out (e.g. by search) where similar documents are classified and then checking the classification scheme.

Step 1 – Preliminary search

Start in either Espacenet or Google Patents, or Lens and enter relevant keywords

Note: 4.1 See Annex Q and Annex R for user guides for Google Patents and Espacenet, respectively.

Step 2 – Check classification

Decide the relevance of found documents based on title, abstract or figures. Then check the CPC symbols of each relevant document.

In Espacenet: click on each CPC symbol to display the description and hierarchy.

Step 3 – Explore classification

When a symbol is considered to be relevant to the search, open the main group in a separate window to explore the rest of the scheme.

IMPORTANT: Make sure that you consult the Definitions, Warnings and Notes whenever they are available.

In Google Patents, the easiest method to check for definitions of CPC symbols is to click on the link to Espacenet and view such definitions in Espacenet interface.

Step 4 – Summary table

Group relevant CPC symbols according to the technical feature that they relate to, for example:

The Statistical approach involves identifying a statistically-relevant group and then checking the correctness of scope, notes, references etc.

In Espacenet: use the search function under the Classification search tab

Expand each main group to browse through the scheme and locate relevant CPC symbol(s).

Check scope, notes, cross-references etc. of the symbols to determine their relevance to the search and repeat Step 3 as above.

Other techniques can be used to locate CPC symbols relevant to a search, including:

  • consulting experts: via 3PT or discussion with subject matter experts for the technology
  • use the CPC Definitions: consult the CPC definition, especially the relationships of a CPC symbol with other large subject-matter areas

  • natural language/text categorisation search engines: IPCCAT (for IPC symbols only)