If an external symbol of the COMMON-LISP package
is not globally defined as a standardized dynamic variable
or constant variable,
it is allowed to lexically bind it
and to declare the type of that binding,
and
it is allowed to locally establish it as a symbol macro
(e.g., with symbol-macrolet).
Unless explicitly specified otherwise,
if an external symbol of the COMMON-LISP package
is globally defined as a standardized dynamic variable,
it is permitted to bind or assign that dynamic variable
provided that the "Value Type" constraints on the dynamic variable
are maintained, and that the new value of the variable
is consistent with the stated purpose of the variable.
If an external symbol of the COMMON-LISP package is not defined
as a standardized function, macro, or special operator,
it is allowed to lexically bind it as a function (e.g., with flet),
to declare the ftype of that binding,
and
(in implementations which provide the ability to do so)
to trace that binding.
If an external symbol of the COMMON-LISP package is not defined
as a standardized function, macro, or special operator,
it is allowed to lexically bind it as a macro (e.g., with macrolet).
If an external symbol of the COMMON-LISP package is not defined
as a standardized function, macro, or special operator,
it is allowed to lexically bind its setf function name
as a function,
and to declare the ftype of that binding.