Source : Free On-Line Dictionary of Computing

Sequenced Packet Exchange
     
         (SPX) A {transport layer} {protocol}
        built on top of {IPX}.  SPX is used in {Novell NetWare}
        systems for communications in {client/server} {application
        programs}, e.g. {BTRIEVE} ({ISAM} manager).
     
        SPX is not used for connections to the {file server} itself;
        this uses {NCP}.  It has been extended as SPX-II.  SPX/IPX
        perform equivalent functions to {TCP/IP}.
     
       
     {(http://developer.novell.com/research/appnotes/1995/december/03/04.htm)}.
     
        [Better reference?]
     
        (1999-05-27)