Flas the $version property string includes the operating system

Flash can manipulate vector and raster graphics, and supports bidirectional streaming of audio and video. It contains a scripting language called ActionScript. Several software products, systems, and devices are able to create or display Flash content, including Adobe Flash Player, which is available free for most common web browsers, some mobile phones and for other electronic devices (using Flash Lite). The Adobe Flash Professional multimedia authoring program is used to create content for the Adobe Engagement Platform, such as web applications, games and movies, and content for mobile phones and other embedded devices.

And Now, the $version property string includes the operating system on which the Player is running. The operating system can be either "MAC", "WIN", or "UNIX".

playerParts = _level0.$version.split(" ");
switch (playerParts[0]) {
case "MAC":
gotoAndStop ("WelcomeMac");
break;
case "WIN":
gotoAndStop ("WelcomeWindows");
break;
case "UNIX":
gotoAndStop ("WelcomeUnix");
}

As of Flash 6, you can use the System.capabilities.os property, which returns a string indicating the operating system and version name. Possible values include "Windows XP", "Windows 2000", "Windows NT", "Windows 98/Me", "Windows 95", and "Windows CE". On the Macintosh, the string includes the version number, such as "MacOS 9.2.1" or "MacOS 10.1.4".

You can make design choices based on the operating system. For example, your movie might load different assets depending on the user's operating system, or you may simply want to record the operating systems of the users who view your movies for statistical analysis.