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When I started using Windows 2000, I found some of the OS's updated command-processor's special features useful for writing batch files. In particular, I often used delayed expansion and the built-in %date% and %time% variables. Although I still supported more Windows NT 4.0 systems than Win2K systems, I soon discovered that I occasionally wrote batch files that wouldn't run on both OSs. I developed an easy method for testing batch files on Win2K and NT 4.0 console shells—I simply copy and rename the command processor for each OS. My test system's Tools folder contains the files w2kcmd.exe (version 5.0.2144.1 from the Win2K release version), w2kcmdp1.exe (version 5.0.2195.1600 from Win2K Service Pack 1—SP1), and nt4cmd.exe (version 4.0.1381.273 from NT 4.0 SP6a). I can quickly start a console session in the appropriate command-line shell version to check batch files for correct functionality.