Microsoft is being sued in a Texas district court by Vertical Computer Systems for alleged patent infringement. 

Vertical Computer alleges that Microsoft's .Net framework violates patent number 6,826,744, which describes "a system and method for generating computer applications in an arbitrary object framework". 

The method "separates content, form, and function of the computer application so that each may be accessed or modified separately", the patent filing states.

Vertical Computer filed the lawsuit on 18 April after claiming that Microsoft infringed the patent following a cease-and-desist order issued on 7 February.

Microsoft's .Net framework and Vertical Computer's patented SiteFlash product create component-based programs in XML which are used to build and control websites.

Vertical Computer is requesting a full jury trial. If the company wins, the ramifications for Microsoft could be far reaching.

Along with a probable substantial payout, Microsoft would have to make significant changes to its .Net system.