anchor.diff:    : PERCENT | PN_LOCAL_ESC
     ;
   
  +// %-encoded sequences are not decoded during processing
   PERCENT // ok
     : '%' HEX HEX
     ;
  
positive.code:   : [0-9] | [A-F] | [a-f]
    ;
  
  // RDF-specific: the backslash (first character) is ignored when parsing the IRI
  PN_LOCAL_ESC  // ok
    : '\\' ('_' | '~' | '.' | '-' | '!' | '$' | '&' | '\'' | '(' | ')' | '*' | '+' | ',' | ';' | '=' | '/' | '?' | '#' | '@' | '%')
    ;
  
negative.code:   ;
  */
  
  
  // TURTLE.g4 says  '"' (~ ["\\\r\n] | '\'' | '\\"')* '"'
  // but the one below is what is written in https://www.w3.org/TR/turtle/#grammar-production-STRING_LITERAL_QUOTE
  STRING_LITERAL_QUOTE
    : '"' (~ ["\\\r\n] | ECHAR |  UCHAR)* '"'
    ;
  