I studied A68 in detail with a friend of mine in 1976, and I've always admired it greatly.  The van Wijngaarden two-level used in the original report was rather opaque, though the revised report was much more readable (and did not only the syntax and the static semantics, but the dynamic semantics as well).  Only when I got a hold of an actual A68 textbook years later did I actually see a straight grammar of the language, which got me interested in the language again.

Sometimes I wonder what would have happened if A68 had become the medium-level language of Unix, and Pascal had become the language of non-Unix, instead of both of them using C.  (The four segment registers of the x86 mirror exactly the way Pascal pointers work: it is statically known whether a pointer points to the stack, the code, the data, or the heap segment.)

John Cowan          http://vrici.lojban.org/~cowan        cowan@ccil.org
And it was said that ever after, if any man looked in that Stone,
unless he had a great strength of will to turn it to other purpose,
he saw only two aged hands withering in flame.   --"The Pyre of Denethor"