docs: function mxObjectCodec(template, exclude, idrefs, mapping)
  {
  	this.template = template;
  	
  	this.exclude = (exclude != null) ? exclude : [];
  	this.idrefs = (idrefs != null) ? idrefs : [];
  	this.mapping = (mapping != null) ? mapping : [];
  	
  	this.reverse = new Object();
  	
  	for (var i in this.mapping)
  	{
  		this.reverse[this.mapping[i]] = i;
  	}
  }