Source : Free On-Line Dictionary of Computing

ICBM address
     
         (Or "missile address") The form used to
        register a site with the {Usenet} mapping project includes a
        space for longitude and latitude, preferably to seconds-of-arc
        accuracy.  This is actually used for generating
        geographically-correct maps of {Usenet} links on a plotter;
        however, it has become traditional to refer to this as one's
        "ICBM address" or "missile address", and many people include
        it in their {sig block} with that name.  (A real missile
        address would include target altitude.)
     
        [{Jargon File}]
     
        (1994-12-15)