The international, non-profit European Committee for Interoperable Systems ("a coalition of Microsoft's largest competitors"[50]) fears that with Silverlight Microsoft aims to introduce content on the web that can only be accessed from the Windows platform. They argue that use of XAML in Silverlight is positioned to replace the cross-platform HTML standard. Effectively, if Silverlight usage becomes widespread enough, users will risk having to purchase Microsoft products to access web content[51].
California and several other U.S. states also have asked a District Judge to extend most of Microsoft's antitrust case settlement for another five years,[52] citing "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," says a Seattle Post-Intelligencer article.
Microsoft has also been criticized for not using the Scalable Vector Graphics standard for Silverlight, which, according to Ryan Paul of Ars Technica, is consistent with Microsoft's ignoring of open standards in other products, as well.[53] However, according to David Betz, an independent .NET technologies specialist, Microsoft would have needed to alter the SVG specification to add .NET integration and UI constructs on top of SVG to make it suitable for scenarios Silverlight uses markup for (UI and vector markup, by default). Consequently, the "choice by Microsoft to use XAML over SVG, served to retain the SVG standard by not adding proprietary technology [to extend SVG]".[54]
Silverlight Wikipedia description
