This way, the special value @code{nil} is not treated like other
symbols, and symbols are not treated like other Lisp expressions.
+@cindex radio, customization types
@item (radio @var{element-types}@dots{})
This is similar to @code{choice}, except that the choices are displayed
using radio buttons rather than a menu. This has the advantage of
list of elements, with @samp{[INS]} and @samp{[DEL]} buttons for adding
more elements or removing elements.
+@cindex restricted-sexp, customization types
@item (restricted-sexp :match-alternatives @var{criteria})
This is the most general composite type construct. The value may be
any Lisp object that satisfies one of @var{criteria}. @var{criteria}
This matches values such as @code{(baz)}, @code{(baz foo)}, @code{(baz bar)}
and @code{(baz foo bar)}.
+@cindex choice, customization types
When the element-type is a @code{choice}, you use @code{:inline} not
in the @code{choice} itself, but in (some of) the alternatives of the
@code{choice}. For example, to match a list which must start with a