The ISCNTRL function checks that an expression consists entirely of control characters.
NOTE: This function is only available in jBASE 4.1 and later.
expression can return a result of any type. The ISCNTRL function will then return TRUE (1) if the expression consists of entirely control characters. The function will return FALSE (0) if any character in the expression is not a control character.
When the ISCNTRL function is used in International Mode the properties of each character are determined according to the Unicode Standard.