anchor.diff:      ;
       
   groupGraphPatternSub
  -    : triplesBlock?  groupGraphPatternSubList* //(f+=graphPatternNotTriples DOT? triplesBlock?)*
  +    : triplesBlock?  groupGraphPatternSubList*
       ;
       
   groupGraphPatternSubList
  
positive.code: 
  IRI_REF
      : '<' (~('<' | '>' | '"' | OPEN_CURLY_BRACE | CLOSE_CURLY_BRACE | PIPE | INVERSE | '`' | '\\' | '\u0000'..'\u0020'))* '>'
  //    | LESS { $type = LESS; }
      ;
  
  PNAME_NS : PN_PREFIX? ':';
  
negative.code:     ;
      
  triplesBlock
      : triplesSameSubjectPath (DOT triplesBlock?)?
      ;
  
  