Microsoft has gained a patent for using the keyboard tab key to move between links on a web page, but enforcing it could prove counterproductive.

The software firm first submitted the application for patent number 6785865 in March 1997.

The patent summary states: "A user may discover and navigate among hyperlinks through the use of a keyboard. For example, a user may press a tab key to discover and navigate to a first hyperlink that is part of a hypertext document.

"The first hyperlink is, in response, given focus and a focus shape is drawn around the text or graphics for the hot region of the hyperlink. If the user again presses the tab key, the next hyperlink is given focus and a focus shape."

Microsoft told vnunet.com: "Navigating through sets of hyperlinks can be tough if someone doesn't have a mouse, something that is a particularly noticeable challenge for some non-PC devices.

"This patent relates to one technique to that can be used to reduce the challenge."

Microsoft stated that, consistent with its intellectual property policy statement, "should others wish to license this patent, we are happy to discuss that possibility with them".

"Microsoft has not recently held any discussions about this patent, and it does not currently map to any particular Microsoft product that is either shipping or in development," the company added.

But John Collins, a partner at legal firm Marks & Clerk, said: "I would be very surprised if Microsoft did anything with this patent.

"They have an asset. But potentially it may be a worthless asset. [Enforcing it] would do it a grave disservice from a public relations point of view."

Collins suggested that a more general problem was the quality of patent granting, which was particularly acute in IT because of the rate of change.

"The whole problem is one of quality, particularly coming out of the US," he said. "The issue for the US Patent Office is the pressure it is under to throughput work."

Collins argued that the standard response from companies challenged as infringing such a patent would be: "We do not infringe it and [second] it is invalid because of prior art."