In a filing last night (PDF, 26 pages), California and several other states asked U.S. District Judge Colleen Kollar-Kotelly to extend most of Microsoft's U.S. antitrust settlement for another five years. The filing formalizes a request that the states previously outlined in court.

In arguing for the extension, the filing cites a number of concerns, including the fear that Microsoft could use the next version of Windows to "tilt the playing field" toward Silverlight, its new Adobe Flash competitor.

That plays into a broader debate over the extent to which Web-based technologies have diminished Windows' power. Here's what Microsoft said on that topic in an Aug. 30 filing (PDF, 12 pages), as part of its assertion that the final judgment in the case has been effective:

"The entire notion that developers were forced to write to the (application programming interfaces) exposed by Windows, and that this constituted a significant barrier to entry that protected the market position of Windows, is being called into qu