Those letters at the end of patent numbers

Just now a loyal reader of my blog asked what those letters and numbers mean at the end of patent numbers. Here are some examples:

click to see PDF
click to see PDF

My reader wondered, what does “A2” mean? What does “A1” mean?

The short answer is that these are “kind codes”.   “A” might mean a published patent application.  “B” might mean a granted patent.  It turns out that each patent office chooses for itself what kind codes it will use and what they mean.  In the USPTO, a kind code of “B1” means a granted patent for which there was no previously published pre-grant publication.  But in EPO, a kind code of “B1” means a second publication for a patent application.  The alert reader might wonder if there is some place where this is all written down.

As so often happens when questions like this arise, I turn to the WIPO web site.  WIPO provides a very helpful 131-page document entitled Inventory of kinds of patent documents listed according to the issuing intellectual property office.  Scroll down to PDF page 46, for example, and you can see the kind codes used by the EPO.  The “A1” in the example above means a first publication by the EPO for a particular patent application.  Scroll down to PDF page 127 and you can see the kind codes used by WIPO for PCT publications.  The “A2” in the example above means a published PCT application without the international search report.

Some intellectual property offices provide “kind code” information on their web sites.  Examples include USPTO and EPO.

2 Replies to “Those letters at the end of patent numbers”

  1. Thanks for this Carl. Over the years, I’ve learned the codes and differences on a very preliminary and general level in the countries I most often file in… I love the 131 page “resource”. More miscellaneous info to cram into my brain and bookmark for the time I might be wondering about a particular case and country.

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