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WO (PCT) publication numbers

There are three different PCT publication number formats:


• From 1978 to 30 June 2002, the format was WOyynnnnn (two digits for the year and five for the serial number).

•  From 1 July 2002 to 31 December 2003, it was WOyynnnnnn (two digits for the year and six for the serial number).

• Since 1 January 2004 it has been WOyyyynnnnnn (four digits for the year and six for the serial number).


In the publication number search field it is now possible to use a single format (WOyyyynnnnnn) for all the above-mentioned PCT publication number formats.