I've never heard that term before and this is the best I could find to explain it.
The kernel debugger that comes with Windows provides information about the computer that is typically not available without the aid of the debugger. Windows can turn on the kernel debugger from the Windows Start-Up menu (Boot.ini). When you turn on the kernel debugger, Windows debugger can output debugging information to a remote debugger for a remote user to analyze. This is typically done at the request of a Microsoft support professional for analyzing a fatal error in Windows that cannot be diagnosed from the Memory.dmp file or when a Memory.dmp file is not produced.
Found at this site: http://support.microsoft.com/kb/151981