While every country uses its own system of identifying granted patents, below are examples that elucidate the numbering scheme for some of the major jurisdictions.

The United States

Granted Patents (Patent Number)

United States (US) Patents were the only published patent documents until 29 November 2000.  Currently, the United States identifies issued patents with a seven-digit number followed by a B1 (indicates a patent not previously published) or a B2 (indicates a patent previously published). E.g., US 6,174,724 B1, shown below. The "B1" and "B2" are referred to as "kind codes".

Published Patent Applications (Publication Number)

Published U.S. Patent Applications are indicated with the year as a four-digit number and a publication number followed by an A1 (for the first publication), A2 (for republication) or A9 (corrected publication). E.g., US 2001/0002490 A1, shown below. This number is also referred to as the publication number on the USPTO PAIR web site.

Application Number (number assigned prior to publication)

In the U.S. there is also an application number that is different than the publication number above. This is the number that is used to identify the case while it is pending with the USPTO. If searching in PAIR, the USPTO refers to this number as the "application number". Application numbers consist of a two-digit "series" number (usually 09, 10, or 11) that is separated from a six-digit number by a hash mark as shown below. In output from the Patent Lens, the hash mark is omitted.

app number


Granted Patents (Patent Number)

European Patents are indicated with a seven-digit number followed by a B1, e.g., EP 0 458 846 B1 (shown below). A B2 number indicates that the claims have been modified after grant.

Applications (Pubication Number)

European Patent Applications use the same numbering system but the number is followed by A1, A2, etc., e.g., EP 0 955 371 A1 (shown below).

International (PCT) Applications

International Applications often simply called PCT Applications because they are filed under the Patent Cooperation Treaty in a receiving office of the World Intellectual Property Organization (WIPO). The publication numbers have a WO, which stands for "world" followed by the year as 2 digits, followed by a publication number, and A1 (first publication), A2 (second publication), etc. e.g., WO 00/34491 A2 (shown below).

There is no such thing as an international or PCT patent; only applications exist in the PCT. See tutorial about international "patents".

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