File Name Extension Guidelines

• Applications that create content in Windows Media Format that contains audio and/or script commands must use the .wma file name extension for that content.
  
  
• Applications that create content in Windows Media Format that contains audio, video, and/or script commands must use the .wmv file name extension for that content.
  
  
• If you want to use the .wma (and the associated audio/x-ms-wma MIME type) or .wax (and the associated audio/x-ms-wax MIME type) file name extensions in your application, you must offer the user a choice between using your application or an existing application as the default. Your application must be capable of rendering audio content and script command content, and of parsing the Windows Media metafile with the .wax file name extension as described in the Windows Media Metafile Elements Reference below.
  
  
• If you want to use the .wmv or .wvx file name extension in your application, you must offer the user a choice between using your application or an existing application as the default. Your application must be capable of rendering audio, video, and script command content, and of parsing the Windows Media metafile with the .wvx file name extension as described in the documentation.
  
  
• Your applications must not use the .asf (and associated video/x-ms-asf MIME type), .asx (and associated video/x-ms-asf MIME type), .wm (and associated video/x-ms-wm MIME type), or .wmx (and associated video/x-ms-wvx MIME type) file name extensions.
  
  
• If you are using the Windows Media Format SDK to build an application which can play Windows Media-based content, you should implement support for Windows Media metafiles.  Your application can then be launched from a Web browser to stream Windows Media-based content.