CASE

 The CASE statement  causes  one  of  several  statements  to  be
 executed.   The  execution  depends  on  the value of an ordinal
 expression called the case selector.

 Syntax:

    CASE case-selector OF
         [[{{case-label-list},... : statement};...]]
         [[ [[;]] OTHERWISE {statement};...]]
         [[;]]
        END


 The 'case-selector' is an expression of an ordinal type.

 The 'case-label-list' is one or more case  labels  of  the  same
 ordinal  type as the case selector, separated by commas.  A case
 label can be a single constant expression, such as 1, or a range
 of expressions, such as 5..10.

 The 'statement' is any statement to be executed depending on the
 values of both the case-selector and the case-label.

 The 'OTHERWISE' clause is executed if  the  value  of  the  case
 selector  does  not  appear  in the case label list.  This is an
 optional clause, but if you omit  it,  the  value  of  the  case
 selector must be equal to one of the case labels.

Additional information available:

Examples