Vertical Computer Systems Inc. is suing Microsoft Corp. for patent infringement related to Microsoft's .Net framework for building Windows-based software.

Vertical filed suit April 18 in a U.S. District Court in Texas alleging that Microsoft has infringed on its Patent No. 6,826,744, for a "system and method for generating web sites in an arbitrary object framework."

The patent is for Vertical's SiteFlash technology, which utilizes XML (Extensible Markup Language) to create a component-based structure to build and efficiently operate Web sites, according to the company's Web site. A Vertical spokesman could not be reached for comment.

The complaint says Microsoft is still infringing on the patent despite Vertical having put Microsoft on notice about it on Feb. 7. Vertical is asking for a jury trial.

Vertical, based in Fort Worth, Texas, describes itself as a global Web services provider. It went public in 2000 but is not listed on a major stock exchange.