Jerry Bell posted some PIE papers and Alan Kay wrote:
> Thanks Jerry!

And a triple thanks from me! The "Layered Approach to Software Design" 
was one of the main refernces in the Us paper ("A Simple and Unifying 
Approach to Subjective Objects", 
http://citeseer.nj.nec.com/smith96simple.html ) and so I wanted very 
much to read it. I had already come to the conclusion that it was 
better to have separate "layer" and "context" objects than to mix them 
as Us did (that sounds strange ;-) and this confirmed it.

-- Jecel