What are cross-references in patent classification and how are they determined?

Cross-references in patent classification are additional classifications assigned to a patent beyond its original classification. They are determined as follows:

1. All mandatory classifications not selected as the original classification become cross-references.
2. Additional discretionary classifications may be added by the examiner.
3. Cross-references must be indicated on the IFW issue classification form.

The MPEP states: 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.

It’s important to note that Digests and cross-reference art collections should also be included in the issuing classification boxes on the IFW issue classification form, but the original classification must never be a digest or cross-reference art collection.

To learn more:

• cross-references
• patent classification
• mandatory classifications
• discretionary classifications