I quoted someone's boss's list of criteria for an OO language, including
>(4a) multiple inheritance,
to which Alan Kay responded:

	Regarding 4a, I think a much better way to do this is with a multiple 
	perspective architecture as in Goldstein and Bobrow's PIE system 
	(done in Smalltalk at PARC).
	
I have some of the blue-and-white reports; they are real gold.
Unfortunately, very few of them are (as yet) available through
http://www.parc.xerox.com/pubs.html, and I don't see PIE even
listed there.  If it's "A Layered Approach to Software Design",
then it's listed, but not available.  I've spent some time looking
for an on-line copy of the PIE paper, does one exist anywhere?
Is the software itself available anywhere?