anchor.diff:  
   fragment
   DIGIT            : [0-9] ;
  +
  +fragment
  +OCT_DIGIT        : [0-8] ;
  +
  +fragment
  +HEX_DIGIT        : [0-9A-Fa-f] ;
                    
   fragment
   LIST             : L I S T ;
  
positive.code: //-----------------------------------------------------------------
  // Connect data rules. 
  //-----------------------------------------------------------------
  connect_data     : L_PAREN CONNECT_DATA EQUAL cd_params+ R_PAREN ;
  
  cd_params       : cd_parameter+
                  ;
  
negative.code: 
  
  //-----------------------------------------------------------------
  // SPX Protocol rules.
  // (PROTOCOL = SPX)(SERVICE = spx_service_name)
  //-----------------------------------------------------------------
  spx_protocol     : spx_params ;
  
  spx_params       : spx_parameter+ ;
  
  spx_parameter    : spx_spx
                   | spx_service ;
  
  spx_spx          : L_PAREN PROTOCOL EQUAL SPX R_PAREN ;
  
  spx_service      : L_PAREN SERVICE EQUAL ID R_PAREN ;
  
  