.dat file

Greetings, Someone I know got a file with a .dat extension. Since I'm their de facto IT geek I thought I'd take a look at it. When I execute the "file" command, I get "Transport Neutral Encapsulation Format". It is not a pure ASCII file and OpenOffice doesn't particularly open it very well. This is coming from not too computer-literate people who would probably have no idea what a Digital Audio Tape looks like. Does anyone know what this could be? TIA & Cheers