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Publication number

The publication number is the number assigned to a patent application on publication. Publication numbers are generally made up of a country code (two letters) and a serial number (variable, 1-12 digits) (e.g. DE202004009768).


The publication numbers of published US applications, however, consist of 10 digits (e.g. US2004046892). Normally only the number of the first publication level is searchable.


The format of PCT (WO) publication numbers has changed over the years:


  • From 1978 until 30 June 2002 it 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).

You can use any of these formats to enter PCT (WO) publication numbers in the Smart search mask, which uses fuzzy logic.


For certain countries, if you know the kind code, we recommend adding it to the end of the number in order to retrieve the document you want. These countries are: AT, AU, BA, BG, CN, DK, FI, IS, KR, NL, NO, PL, SK, UY, TW, YU, except when the kind code is A.


In the publication number field, you may enter a maximum of ten numbers which will automatically be separated by the default operator OR.


When typing in a publication number, do not leave any spaces between the country code and the number.


To retrieve all the documents having a particular country code in combination with other search criteria (for example the date), all you have to do is enter the country code in the publication number field in combination with, in this example, the date in the publication date field.


For more information on Espacenet, see the following pages: