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.
