Hi Cees,
 
     I like your arguments about the triad: Kernel, Core and Base.
     
     In my mind, these corresponds to Implementor, Developer 
     and EndUser configurations.

    End users should not try to modify what below the Base. 

    Likewise, developers should not try to modify Kernel.

    Implementors should not try to make a mess at this level. ;-)
    
    For the Kernel, when it is cleaned up and factored out,
    a MicroKernel might emerge as well (think 3plus4).
 
    The key word is extensibility.

    I think this structuring is very important, considering that
    besides the good old faithful Squeak now we have also
   Croquet, Scratch, Squeak-E and not to forget the excellent
   MultiMediaSqueakWeatherProofRoofTopWetherStation
   (phew, what a mouthful ;-)

    With this structure, hopefully, each of these would fork 
    and extend Squeak at certain well known level in a 
    cooperative manner.

    Then a lot of energy can be saved for other things instead
    of reinventing wheels of all shapes and sizes :-)
 
    Cheers,

    PhiHo.