+Note that the response type "yn" is equivalent to "restrictchar yn".
+Because "restrictchar" is case-sensitive, the user is expected
+to enter "y" or "n" in lowercase only.
+
+Note that the response type of "email" does not actually
+guarantee that the returned value is a well-formed RFC-822
+email address, nor does it accept all well-formed RFC-822 email
+addresses. What it does is to restrict the returned value to a
+string that is looks reasonably likely to be an email address
+in the "real world".
+