anchor.diff:  // R910
   readStmt : 
   READ  LEFTPAR  ioControlSpecList  RIGHTPAR    (   inputItemList   )?  
  -| READ format   (    COMMA   inputItemList   )?  
  +| READ fformat   (    COMMA   inputItemList   )?  
   Newline
   ;
   // R1115
  
positive.code: ;
  // R705
  addOperand : 
    (   addOperand multOp   )?   multOperand
  ;
  // R704
  multOperand : 
  
negative.code: // R913
  ioControlSpec : 
    (   UNIT  EQUALS    )?   ioUnit
  |   (   FMT  EQUALS    )?   fformat
  |   (   NML  EQUALS    )?   namelistGroupName
  | ADVANCE  EQUALS  scalarDefaultCharExpr
  | ASYNCHRONOUS  EQUALS  scalarCharInitializationExpr
  