Tests whether an external format spec is valid.
external-format
valid-external-format-p ef-spec &optional env => bool
ef-spec
An external format spec.
env
An environment across which the spec should apply.
bool
t if ef-spec is a valid spec; nil otherwise.
t
nil
This predicate tests whether the external format spec given in ef-spec is valid (in the environment env ).
(valid-external-format-p '(:Unicode :eol-style :lf))
LispWorks User Guide and Reference Manual - 21 Dec 2011