If the display is set to the Windows XP Theme, and a manifest file is used, the value is "MS-WINXP".
If the display is set to the Windows XP Theme, and a manifest file is not used, the value is "MS-WIN95".
If the display is set to the Windows Classic Theme, the value is "MS-WIN95".
For character interfaces, the value is "TTY".
ABL supports an override option that enables applications that need the WINDOW-SYSTEM attribute to return the value of "MS-WINDOWS" for all Microsoft operating systems to do so. To establish this override capability, define the WindowSystem key in the Startup section in the current environment, which might be the registry or an initialization file. If the WindowSystem key is located, the WINDOW-SYSTEM attribute returns the value associated with the WindowSystem key on all platforms.