The US Patent and Trademark Office has confirmed the validity of a Xerox software patent, clearing the way for Xerox to pursue a patent infringement case against 3Com.

The lawsuit alleges that the handwriting-recognition software used in 3Com's Palm devices belongs to Xerox.

In January 1997, Xerox received the patent for Unistrokes - a handwriting technology that handles information input into a computer by printing letters in a special shorthand. Three months later, Xerox sued US Robotics in US District Court in Rochester, New York, claiming it used the technology in its strong-selling Palm handheld computers.

Both 3Com and Xerox recently asked US District Court Judge Michael Telesca, who is hearing the case, to lift a stay so the suit can proceed, according to a clerk for Telesca.

The judge has not yet lifted the stay, but is going to schedule a conference soon, the clerk said. In October, Telesca denied 3Com's motion to dismiss the case.

Telesca imposed the stay pending the ruling from the Patent and Trademark Office, which "from Xerox's standpoint is very encouraging as we move forward in this litigation," said Christa Carone, a spokeswoman for Xerox.

Since the patent infringement suit was filed, US Robotics has been bought by 3Com, which recently spun off its Palm Computing subsidiary into an independent company that was expected to begin selling stock publicly this month.

3Com did not return a call seeking comment about the suit.

Xerox has become more diligent about protecting its intellectual property in recent years. The company also sued Hewlett-Packard Co. alleging some of the company's inkjet printers infringe on Xerox patents. That case was dismissed last September, but Xerox has said it will appeal.