+The following subroutines provide (hopefully) useful information about the
+values retrieved from a reader.
+
+=head3 PSPP::format_value ($value, $variable)
+
+Returns a scalar containing a string representing C<value> formatted according
+to the print format of C<variable>.
+In the most common usage, C<value> should be a value of C<variable>.
+
+
+=head3 PSPP::value_is_missing ($value, $variable)
+
+Returns non-zero if C<value> is either system missing, or if it matches the
+user missing criteria for C<variable>.
+
+=cut