code: //==============================================================================
  //	
  //	Copyright (c) 2002-
  //	Authors:
  //	* Andrew Hinton <ug60axh@cs.bham.ac.uk> (University of Birmingham)
  //	
  //------------------------------------------------------------------------------
  //	
  //	This file is part of PRISM.
  //	
  //	PRISM is free software; you can redistribute it and/or modify
  //	it under the terms of the GNU General Public License as published by
  //	the Free Software Foundation; either version 2 of the License, or
  //	(at your option) any later version.
  //	
  //	PRISM is distributed in the hope that it will be useful,
  //	but WITHOUT ANY WARRANTY; without even the implied warranty of
  //	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  //	GNU General Public License for more details.
  //	
  //	You should have received a copy of the GNU General Public License
  //	along with PRISM; if not, write to the Free Software Foundation,
  //	Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  //	
  //==============================================================================
  
  package userinterface.util;
  
  import java.util.*;
  
  public interface PropertyOwner extends Comparable<Object>
  {
  	// One for each type of owner
  	public int getUniquePropertyID();
  
  	// One for each owner
  	// This will be displayed when only
  	// this owner is being displayed.
  	public String getDescriptor();
  
  	// One for each type of property collection
  	// When only one owner is being displayed,
  	// we see the result of this method, and then
  	// the result of getDescriptor.
  	// If there is more than one owner being
  	// displayed, we see the number of
  	// owners, then the result of this method
  	// followed by an "s".
  	public String getClassDescriptor();
  
  	public int getNumProperties();
  
  	public SingleProperty getProperty(int index);
  
  	public void registerObserver(Observer obs);
  }
  