Source : Free On-Line Dictionary of Computing

Telocator Alphanumeric Protocol
     
         (TAP, or "IXO", "PET") A {protocol}
        for submitting requests to a {pager} service.  IXO/TAP is an
        {ASCII}-based, {half-duplex} {protocol} that allows the
        submission of a numeric or alphanumeric message.
     
        {Examples, protocol description, clarifications
        (ftp://mirror.lcs.mit.edu/telecom-archives/technical)}.
     
        See also {RFC 1568}.
     
        (1996-04-07)