Microsoft has withdrawn one of its patent claims against Barnes & Noble in a case before the International Trade Commission.

The case stems from Microsoft's allegations that Barnes & Noble's Nook e-reader and Nook Color tablet, which run on Google's Android operating system, infringe on some of MIcrosoft's patents.

Microsoft said in its ITC filing that it was withdrawing its infringement allegation over "the '522 patent" (which covers tabbed control) in order "to streamline the case and conserve the resources of the commission, as well as those of the parties."

The motion to withdraw that claim "is not a concession on the merits of such claims," Microsoft said in its filing.

That leaves three MIcrosoft patents that the software company claims BN violated. Those involve annotation software that allows readers to make notes on e-books separate from the book, software that allows people to select and make a text area larger or smaller, and technology that helps readers perceive faster browser downloads by displaying text first, then the background.