Does Defmacro establish a block?

[Rob MacLachlan <RAM@CMU-CS-C.ARPA>]

    It is clearly stated in the manual that defun establishes a block
named with the function name.  This is a feature which I use
extensively.  The question is "Which of the other def-mumbles establish
a block as well, and if not why not?"

    Moon's answer is "They all do."  Admittedly returning out of the
body of a deftype will probably not often be useful, but this
definition has the advantage that it is consistent.  This consistency
doesn't cost anything, so we might as well do thing this way.

  Rob