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Re: loop macro

	From: Jeff Dalton <jeff%aiva.edinburgh.ac.uk@cs.ucl.ac.uk>

	Re Maryland loop macro: one thing is still unclear to me:
	are the iteration variables always stepped in parallel (a
	la DO)?  Is there any way to have it done sequentially
	(DO*)?  One reason for linking words in ZetaLoop is to
	distinguish these cases.

Always via DO -- they are init'd in parallel; you can use LET to
bind other variables which may be ref'd.  Of course, on the iteration
steps, the variables are updated in sequence.  The Maryland macro
always expands to a DO with, possibly, one or more LET's around it.

I don't really remember needing to use a DO* type binding of
iteration variables.  I guess I would use a LET to bind some common
value and use it in the init part of the iteration values.