public Field getNextUnattributedClass()	{
	
		//System.out.println("Group.getNextUnattributedClass() : " + this + " " + this.classes);
		
		Iterator<Field> iter = this.classes.keySet().iterator();

		Field f;
		
		while (iter.hasNext())	{
			
			f = iter.next();		
			if (this.links.getLinks(f).size() == 0)
				return f;
		}
		
		return null;
	}