PB Quality Standards for National and International Patent Classification

The following standards ensure that the application of Classification codes:

  • Contributes to the efficient operation of the Patent Office, by making searches more efficient, more reliable, and easier to design;
  • Facilitates the retrieval of Canadian patent documents(applications and granted patents), through the use of the International Patent Classification (IPC);
  • Contributes to the proper work flow of the Patent Branch by assigning the First (F) IPC symbol to a patent application.

Assignment of IPC

Patent documents are classified consistently, according to the rules stated in the Guide to the IPC, notably Articles 39-41, 45, 67-75, 77-80, 90-101, 103, 105, 118-123, 127-131, 133, 141-143, 147-156 and CIPO’s internal precedence rules for the First IPC symbol.

  • At least one inventive classification symbol is assigned to the subject matter of each and every claim of a patent document, when construed in light of the specification and, if any, drawings (“technical disclosure” of the Guide of the IPC);
  • Relevant inventive classification symbols are assigned to any additional subject matter in the description or drawings that appears to be an addition to the state of the art;
  • Relevant non-inventive classification symbols are assigned to any additional subject matter in the description, claims or drawings that may be of interest to a searcher.


Review of IPC symbols is conducted upon receipt of the corresponding task from examination and giving due consideration to the suggestions presented. Upon completion of the task and the assignment of new codes as appropriate, the task is reassigned to proper examination queue.


When necessary, the rationale for classification symbols is clearly explained in notes, particularly:

  • the reasoning for selecting the First IPC symbol (F);
  • when certain classification symbols apply to only subsets of claims;
  • when certain classification symbols are directed toward subject matter found only in the description or drawings.


Patent classification is carried out according to the priority order, and within the established time frames.