LISP-SYMBOL-REDEFINITION

[David A. Moon <Moon@STONY-BROOK.SCRC.Symbolics.COM>]

I guess we have to go with LISP-SYMBOL-REDEFINITION:DISALLOW.  We
unfortunately have to include the part that prohibits lexically
shadowing (redefining is the wrong word here) functions in the
LISP package with FLET or LABELS or MACROLET (the latter is 
missing from the writeup), since research into straightening out
the syntactic environment of macroexpansion isn't mature enough
to put into a standard yet.

You can drop the part about lexically shadowing constants, since the 3rd
paragraph on CLtL p.69 already covers this.  It's unclear what the CLtL
sentence about bindings of lexical variables of the same name is
supposed to mean: since CL does not include an UNSPECIAL declaration,
there is no way to express such a binding.