In the 1960s Marshall McLuhan was the creator of the terms ‘the medium is the message’, ‘global village’. He was later named ‘Patron Saint’ of Wired magazine. One of his most interesting ideas is the Tetrad . To make a tetrad, you start with some ‘medium’ or innovation. In this case, I pick the Free Software Licenses, such as GPL and try to place them into a context of what came before it and what is to come because of it. The medium enhances something, obsoletes something, retrieves something, and finally reverses into something, somewhat like a star collapsing in on itself.

I can textually show a tetrad like this:

                      	        [ reverses ]	  	    
[ enhances ]  
                       [ medium ]
		                    [ obsoletes ]
     [ retrieves ]

Here is my tetrad for free software licenses:

                             [ 3rd party distributions ]	  	    
[ free software options ]  
                [  free software license  ]
	                                [ private software dev. ]
     [ scientific collaboration ]

This is to good exercise in trying to put words to ideas about a medium and I believe often leads to a desire to better name elements of the tetrad, especially the ‘reserve’ field since such thing may not have yet happened and thus may not have a great term coined yet. In the above model, the free license disappears and eventually an outsider would only see the 3rd party software distribution. So something spectacular appears less so; all of the collaboration of linux is reduces to, for example, a statement like: “Oracle is supported only under Red Hat Linux and we must buy a license from Red Hat in order to use it professionally.”

Here is a tetrad for a software package that we use called Appworx Job Scheduler. In this case, it is actually in the reverses field because it has passed its prime and been bought by another company called UC4:

                      [ appworx/uc4 ( half refactored quagmire) ]	  	    
[ oracle database ]  
                       [ sqloper ]
		              [ Windows Job Sched. and cron ]
     [ JES job scheduler ]