Procedure Spad (var s:      packed array [lo..hi:integer] of char;
                    chzap: char;
                    chpad: char    );
   EXTERNAL;
{*USER*
  Procedure will take a string and replace trailing "chzap" chars
  with "chpad" chars.  Works on type0 strings starting at end of
  string, and type1 strings starting at "hi", both working backwards
  until a non-"chzap" character hit.
}