anchor.diff:      ;
   
   datasetClause
  -    : FROM NAMED? iriRef
  +    : FROM NAMED? iri
       ;
   
   whereClause
  
positive.code: blankNodePropertyList
      : OPEN_SQUARE_BRACKET propertyListNotEmpty CLOSE_SQUARE_BRACKET
      ;
      
  collection
      : OPEN_BRACE graphNode+ CLOSE_BRACE
      ;
      
  graphNode
      : varOrTerm | triplesNode
      ;
  
  varOrTerm
      : var | graphTerm
      ;
  
  varOrIRIref
      : var | iriRef
      ;
  
  var
  
negative.code:     ;
  
  builtInCall
      : aggregate
      | STR OPEN_BRACE expression CLOSE_BRACE
      | LANG OPEN_BRACE expression CLOSE_BRACE
      | LANGMATCHES OPEN_BRACE expression COMMA expression CLOSE_BRACE
      | DATATYPE OPEN_BRACE expression CLOSE_BRACE
  