DEFINITION MODULE CharClass;
 
  (* Classification of values of the type CHAR *)
 
PROCEDURE IsNumeric (ch: CHAR): BOOLEAN;
  (* Returns TRUE if and only if ch is classified as a numeric character *)
 
PROCEDURE IsLetter (ch: CHAR): BOOLEAN;
  (* Returns TRUE if and only if ch is classified as a letter *)
 
PROCEDURE IsUpper (ch: CHAR): BOOLEAN;
  (* Returns TRUE if and only if ch is classified as an upper case letter *)
 
PROCEDURE IsLower (ch: CHAR): BOOLEAN;
  (* Returns TRUE if and only if ch is classified as a lower case letter *)
 
PROCEDURE IsControl (ch: CHAR): BOOLEAN;
  (* Returns TRUE if and only if ch represents a control function *)
 
PROCEDURE IsWhiteSpace (ch: CHAR): BOOLEAN;
  (* Returns TRUE if and only if ch represents a space character or a format effector *)
 
END CharClass.