type

  listlink = ^listcell;

  listelement = integer; {This has been assumed INTEGER for this file}
                         {Alpha-Pascal doesn't support 'type' imports}
                         {User may modify to type desired.}
  listcell = record
    left : listlink;
    right : listlink;
    element : listelement;
  end;

  list = listlink;

  listposition = listlink;    

  stack = list;
  stackelement = listelement;

.