derived types

[MLY.G.SHADES%MIT-OZ at MIT-MC.ARPA]

what we really want is to define c, as knuth did with mix, to say that
char has a minimum holding value of 2^8-1 and short 2^16-1 and long
2^32-1 with int being bound to either short or long.  this eliminates
the implementation problems on all machines because all you do is
select the smallest element that will hold the specified type.

                          shades at mit-oz.arpa