Each patent is published with a patent number upon issuance. The patent number is frequently followed with a kind code, which conveys information about the patent or its prosecution history. Other patent documents include kind codes as well. In 2001, the USPTO began including kind codes that aligned with the World Intellectual Property Organization’s standards.
The US uses many kind codes to designate different information on a patent document. The list below shows a few of the more frequently-used codes.
- A1 – Patent Application Publication
- A2 – Republished Patent Application Publication
- B1 – Patent (having no pre-grant publication)
- B2 – Patent (having a pre-grant publication)
- C1, C2, C3… – Reexamination Certificate
- E – Reissue Patent
- P1, P2, P3 – Plant Patent
- P4, P – Plant Patent Application Publication
- S – Design Patent
As you can see, the letter indicates the type or substance of the document, and the trailing number, if any, informs the history. A 1 frequently indicates that this publication is the first publication in the prosecution history, while a 2 means that at some previous point, the application was published. Now what drives me crazy about this list is that a design patent is identified with an “S.” I imagine this a result of a translation of the word “design” somewhere at WIPO, but it does seem that a design patent should carry a “D” rather than an “S.” But, then again, design patents are unique in that the patent number carries a leading “D.” Which makes inclusion of the S a bit redundant.