While the SELECT/SELECTONE statements can be used similar to the
  CASE statement.  For example,

     SELECT expression OF
      1: WRITELN('ONE');
      2: WRITELN('TWO');
      OTHERWISE WRITELN('not ONE or TWO')
      END

  a more subtle (and powerful)  form  uses  the  Boolean  constant
  'TRUE' as the select-selector.  For example,

     SELECTONE True OF
      expression < 10: WRITELN('Value is small');
      expression < 100: WRITELN('Value is medium');
      expression < 1000: WRITELN('Value is big');
      OTHERWISE WRITELN('Value is too big');
      END

     SELECTONE True OF
      expression = "AAA": writeln('String is AAA');
      expression = "BBB": writeln('String is BBB');
      expression = "CCC": writeln('String is CCC');
      OTHERWISE writeln('unknown string');
      END

     FOR i := 1 TO 10 DO
       SELECT True OF
        ODD(i): WRITELN('value ',i:1,' is odd');
        (i MOD 3) = 0:
                WRITELN('value ',i:1,' is also a multiple of 3');
        END;