I'm exploring statuses, patent expiries and kind codes in a three part series of articles. The first article on statuses can be found here, and the second article on patent expiries can be found here.
This third, and final, instalment takes a closer look at how to read kind codes.
If you've ever looked at a patent specification you've seen a kind code. They are the As, Bs and Cs, usually with a number, tacked on to the end of a patent number.
Kind codes have meaning. They tell you what significant events have occurred in the lifecycle of a patent. Those significant events range from being filed to grant to amendment, and can also tell you what type of application you are looking at. In Part 2 of this series on patent expiries, we considered the shorter patent terms for utility model applications. Kind codes will tell you if you have one.
In Australia, there are kind codes starting with A, B and C. Standard applications such as convention completes or national phase entries get the kind code A1 with their first publication, and B1 when they are granted. If they are amended post-grant, they get the kind code C1. Corrections to bibliographic data get A8/B8/C8 kind codes when the corrected specification is published.
The utility model/innovation patent applications get A4 or B4, and even C4 if corrected during its short lifespan.
The United States has a set of similar looking kind codes but they don't mean exactly the same things. Published applications get A1, or A9 if corrected, but the granted patents get B1 if there was no A1 published (first published on 15 March 2001), and B2 if there is an A1 published.
Other United States kind codes include a C for a re-examined patent, and E for a re-issued patent.
Patent Cooperation Treaty, or PCT, applications don't get granted so we generally just see a range of "A" kind codes. There is A1 when the specification is published with a search report, A2 when it isn't, and A3 when they do eventually publish the search report.
Other letters used often in kind codes are U or Y for utility model patents, and T for translations of foreign language specifications. Sometimes, in the spirit of the Zeroth Law of Thermodynamics, where an extra, more fundamental law was determined after the other three laws, provisional applications are given an A0 kind code, because they are the initial application upon which the rest of the patent family arises.
Each country has its own set of kind codes, some with just a couple to indicate filing and grant, and many more with an extensive array, especially where they have utility model applications and working in a number of languages. There are many lists available online, some for specific countries if that's all you need, but this list from Clarivate is a nice summary of kind codes around the world.
To tie this series together, while you're searching, you can use kind codes on the fly to see where a patent is up to, the patent expiry date to see if it could be alive, and the status to determine if it is truly dead or alive.
The content of this article is intended to provide a general guide to the subject matter. Specialist advice should be sought about your specific circumstances.