Microsoft withdrew a patent from the list of ones that it claims Barnes & Noble violates with its Nook e-readers in the software giant's case against the bookseller before the U.S. International Trade Commission.

The software giant filed a motion yesterday to remove the so-called "522 patent," which covers the method of displaying tabs, like those in a browser. A Microsoft spokeswoman said it decided to withdraw the patent from the dispute to focus on its case.

The Nook Color, a target of Microsoft's lawsuit.

(Credit: Barnes & Noble)

"We removed the patent from the ITC investigation to streamline and simplify the issues to be considered at the hearing as is often done in ITC proceedings," the company said in a statement. "It was not a concession on the merits."

The agency will hold hearings on the case on Monday.

The dispute is part of Microsoft's broader assault on Google's Android operating system, which powers Barnes & Noble's Nook e-reader and the Nook Color tablet. Microsoft is also suing Motorola for using Android. And it's reached licensing deals with several device makers that use the operating system, including HTC and LG.

On Wednesday, Administrative Law Judge Theodore Essex narrowed the case some, granting Microsoft's request to dismiss Barnes & Noble's "patent misuse" defense. That left Barnes & Noble to challenge only the validity of the patents under dispute, and whether its devices infringe on them.

Now the companies will only spar over three patents. The so-called "233 patent" covers the method by which users can take notes in digital books without altering copyrighted work. The "372 patent" relates to technology that displays text before displaying backgrounds to give the perception of a speedier download. And the "551 patent" covers the way users select the area around text and alter its size.