sets                     Set of Elements                       Data Structure

    Pascal allows the definition of a set of an ordinal type (Integer
    subrange, Char, Boolean, enumerated). No actual values are stored in a
    set;, instead, a bit is set indicating whether or not a given value is
    currently present in the set. The general format is:

         type
           <tname> = set of <ord type>;

         var
           <vname> = set of <ord type>;

    where <ord type> is a Char, Boolean, Integer, or enumerated type, such
    that it is a subrange with no more than 256 values.

    Set operators (including set membership) are defined.

  -------------------------------- Example ---------------------------------

           type
             Days = (Sun,Mon,Tues,Wed,Thur,Fri,Sat);

           var
             Able : set of Char;
             Iota : set of Days;
             Fred : set of Byte;

           begin
             Able := ['B'..'K'];
             Iota := [Sun,Tues,Fri];
             Fred := [1..3,5,7,11,13,17,19,23,29]
           end.