MPEP § 903.07
U.S. utility patents and U.S. utility patent application publications published after December 31, 2014 do not receive classifications within the USPC and only receive classification designations within the CPC. Only U.S. design and plant patents and U.S. plant patent application publications continue to receive classifications within the USPC.
When an application is passed to issue, it is the duty of each primary examiner to personally review the original classification and cross-referencing made by their assistants in the issuing classification boxes on the Issue Classification sheet. This form provides space for the full name of the "Primary Examiner" to show that the review has been made. An examiner with full signatory authority who acts personally on an application and sends it to issue should stamp and sign their name on the Issue Classification sheet ONLY in the "Primary Examiner" space.
An application, properly classified at the start of examination, may be classified differently when it is ready for allowance. The allowed claim should be reviewed in order to determine the subject matter covered thereby. It is the disclosed subject matter covered by the allowed claim that determines the original and any mandatory cross-reference classification of U.S. patents.
After all mandatory classifications have been determined, the classification to be designated as the original (OR) is determined. If all mandatory classifications are in the same class, the original classification is the mandatory classification that, looking at the schedule from the top down, is the most indented subclass array in which any classifications are assigned, in certain circumstances (e.g., the genus-species array), however, modifications of this rule may apply. See the "Examiner Handbook on the Use of the U.S. Patent Classification System".
If the mandatory classifications are in different classes, the original classification is determined by considering, in turn, the following criteria:
It should be noted that the criteria, supra, may be superseded by
Once the controlling class is determined, the original classification, looking at the schedule from the top down, is the mandatory classification that is the most indented subclass of the first subclass array in which any classifications are assigned.
For a more complete discussion of this subject, see the "Examiner Handbook on the Use of the U.S. Patent Classification System" which is available online to USPTO personnel from the Classification Home Page under the heading "General Training". The Classification Home Page (https://ptoweb.uspto.gov/patents/classification-resources/ ) is accessible from the desktop via the Patent Examiner’s Toolkit.
Once the original classification is determined, all remaining mandatory classifications are designated as cross-references, as are any additional discretionary classifications that the examiner wishes to apply to the patent.
The examiner must complete the issue classification sheet to indicate the class and subclass in which the patent should be classified as an original and also the classifications in which it should appear as a cross-reference. The examiner should be certain that all subclasses into which cross-references are placed are still valid.
All examiners must include alpha subclass designators in the issuing classification boxes on the issue classification sheet at the time of issue when appropriate. This applies to both the original classification and the cross-reference classification. Any time that a patent is being issued in or cross-referenced to a subclass containing alpha subclasses, the alpha designation for the proper alpha subclass must be included. No other designation is permissible. Inclusion of only the numeric designation of a subclass which includes an alpha subclass designation is an incomplete and improper entry. A numeric subclass from which alpha subclasses have been created is designated with an "R" (denoting residual), and if the patent does not fit an indented alpha subclass, the "R" designation must be included. It is permissible to place multiple copies of a patent into a single set of alpha subclasses.
Digests and cross-reference art collections should also be included in the issuing classification boxes on the issue classification sheet, but the original classification must never be a digest or cross-reference art collection. The indication for a copy of a patent in a digest or cross-reference art collection must be in the cross-reference area of the issuing classification boxes. A digest must be identified by class number, alpha characters DIG, and appropriate digest number.
U.S. patents cannot be classified in subclasses beginning with "FOR," since these are exclusively for foreign patents.
Where an official classification order affects an application already passed to issue, the Office of Patent Classification oversees any necessary changes. Patents issuing from applications which already have been sent to the printer will be reclassified.
Throughout the examination of a design or plant application, systematic notes should be kept as to cross-references needed either due to claimed or unclaimed disclosure. Examiners handling related subject matter should be consulted during prosecution (whether they handle larger unclaimed combinations or claimed or unclaimed, but disclosed, subcombinations), and asked if cross-references are needed.
Each consultation involving a question of the propriety of the classification of subject matter and/or the need for a cross-reference must be recorded in the SEARCH NOTES box on the file wrapper and must include: the name of each examiner consulted, the date that the consultation took place, and the results of the consultation including the consulted examiners’ or examiner’s indication of where claimed subject matter is properly classified and where subject matter disclosed but unclaimed is properly classified and whether or not a cross-reference is needed.
A cross-reference MUST be provided for all CLAIMED disclosure where possible and inserted in the issuing classification boxes at time of issue.