@samp{-+=*/}. Such names require no special punctuation; the characters
of the name suffice as long as the name does not look like a number.
(If it does, write a @samp{\} at the beginning of the name to force
-interpretation as a symbol.) The characters @samp{_~!@@$%^&:<>@{@}} are
+interpretation as a symbol.) The characters @samp{_~!@@$%^&:<>@{@}?} are
less often used but also require no special punctuation. Any other
characters may be included in a symbol's name by escaping them with a
backslash. In contrast to its use in strings, however, a backslash in