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Searching Application Numbers (continued)

For this search, I will again use File 351, Derwent World Patents Index.

Let's take a look at the application number we found in the U.S. patent for the Woosh and search that application number in Derwent.

I start by typing BEGIN 351 in the command textbox. Next, I enter the application number according to the chart above for a continuing series country in the command textbox: s an=us 400997

?s an=us 400997
      S1       0  AN="US 400997"

Oh no, I obtained zero patent applications using the application number US 400997. That's strange!

In some countries, however, application numbers are reused. Thus, the application number may refer to different inventions with the only difference for the application number being in the date of application.

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