code: function x224DataHeader() {
  	var self = {
  		header : new type.UInt8(2),
  		messageType : new type.UInt8(MessageType.X224_TPDU_DATA, { constant : true }),
  		separator : new type.UInt8(0x80, { constant : true })	
  	};
  	return new type.Component(self);
  }
docs: Header of each data message from x224 layer
  @returns {type.Component}