-@deftypefn {Function} {} MISSING (@var{variable or expression})
-@var{num} may be a single variable name or an expression. If it is a
-variable name, results in 1 if the variable has a user-missing or
-system-missing value for the current case, 0 otherwise. If it is an
-expression, results in 1 if the expression has the system-missing value,
-0 otherwise.
-
-@quotation
-@strong{Please note:} If the argument is a string expression other than
-a variable name, MISSING is guaranteed to return 0, because strings do
-not have a system-missing value. Also, when using a numeric expression
-argument, remember that user-missing values are converted to the
-system-missing value in most contexts. Thus, the expressions
-@code{MISSING(VAR1 @var{op} VAR2)} and @code{MISSING(VAR1) OR
-MISSING(VAR2)} are often equivalent, depending on the specific operator
-@var{op} used.
-@end quotation
+@deftypefn {Function} {} MISSING (@var{expr})
+Returns 1 if @var{expr} has the system-missing value, 0 otherwise.