WindowsCore
The installer sets this variable to a nonzero value if the target system is running a core (non-UI) version of Windows. Currently, only Windows Server 2008 has Core installations (in addition to full installations).
Background
Windows Core versions do not have a graphical user interface shell, but only a command line interface. As such, they do not support all shell-oriented Windows features. However, the InstallMate 11 Setup.exe program runs normally on these systems and can be used both in interactive and in silent mode.
Usage
You can refer to this variable as <WindowsCore>. In conditional expressions you can omit the brackets and simply use WindowsCore as a test for a Windows core installation. Set automatically by all installers.