readtable and # "syntax"

[Steven Haflich <smh@mit-ems.ARPA>]

There are other ways in which reader # syntax is underspecified in
CLtL.  Consider:

	(setq r (copy-readtable))
	(set-syntax-from-char #\( #\) r)
	(set-syntax-from-char #\) #\( r)

In readtable r the parens should now have exchanged their normal
functions.  When readtable r is in effect, which of the following is
correct reader syntax?

	)defstruct foo a b(	;Ugh!
	#S(foo 1 2)
or
	)defstruct foo a b(
	#S)foo 1 2(

The issue is not clear from CLtL, which avoids calling the text after #S
a "list" and just generally refers to "this syntax".