During prior art searches or freedom to operate searches one encounters patent application numbers that have a "(A)" after the number. If you research other publications, of the same invention, or even family trees all that one finds are application numbers that end with "(A)". Yet if you do a legal status search on some of the application numbers you find that a patent has been granted. There seems to be no ordinary expected valid patent number that ends with a "(B)". How is this possible? Regards, Deon.

2 Answers 2


That's not accurate. For many countries, the number of the patent is followed actually by a "B". However, it's not a rule.

You probably come across the "A" publications, because (again for most countries) "A" is used for the patent applications of US, Europe and PCT-applications and those offices are they main tools for databases. And as applications always precedes the grant of the patent, you get "A" documents. I think it's only incidental.

So, for USA, patent applications are usually cited with their publication number and they look like that: US-yyyy-nnnnnnnnn-A(1) and for patents: US-nnnnnnn-B(2). Note that there are also application numbers, another characteristic of the file (not the document) - rarely used.

For Europe, Canada, Australia, you have the same (publication) number in all cases, when it's an application you have (number format)+A, for granted patent (number format)+B. For China the old numbering system provided different numbering between applications and patents, now it's like Europe and the like. Japan is also similar to US, different number for applications and patents (here the application number is a better tool).

For PCT applications you will only see "A" publications because a "global" patent system does not exist, all you can do is file the application through this central procedure (PCT) and split it later to countries and regions you are interested in. Those look like that: WO-yyyy-nnnnnn-A(1 or 2 or 3).

Letters A and B are named "kind codes" and you can always find out what they stand for in each country by googling it. There you will also find explanations for the one-digit-number following "A" or "B" (A1, A3, B2, etc).

I suggest you use the espacenet platform, which is free and presents the INPADOC patent family in a very comprehensive way. I work with that 80% of my day, when doing FTO work and look across patent families.


Hope you find all the above useful, presonally it took me a while to get the picture.

  • The long and the short of it is that if you do a FTO search you cannot accept that if you come across a publication number with an "A" suffix it won't affect your FTO zone. I use Espacenet myself and I also use the patent family feature as well. I accept that one of the reasons you cannot ignore a number with an "A" suffix is that the application may mature into a granted patent. So from what I understand from you an "A" suffix number will only be indicated as a granted patent if it is a Japanese or Chinese patent. Your assistance is much appreciated. Dec 4, 2016 at 7:37

You are right up until the point you mention the "A" suffix.

Most of us, I suppose, gather information for major markets, so you can make a list where you will gather kind codes for applications and granted patents. EPO, USA, Australia, Japan use a "B" for granted patents. Canada uses a "C". China used to have a "C" for granted patents, now it's a "B". All of them use "A" for applications. When you come across an "A" you might want to take a look at the examination stage in a few major offices (EPO and USPTO) to take an idea of what are the odds of this maturing into a patent. If you see a "B" you definitely need to see if it still valid, the renewal fees may have stop being paid, so then the patent will lapse. The patent may even be under litigation, or, for an EP patent, it might be validated only in certain countries and not the one you are interested in. I hope I didn't make it worse here :)

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