anchor.diff:      
   SEPARATOR : ('S'|'s')('E'|'e')('P'|'p')('A'|'a')('R'|'r')('A'|'a')('T'|'t')('O'|'o')('R'|'r');
   
  -IRI_REF
  +IRIREF
       : '<' (~('<' | '>' | '"' | OPEN_CURLY_BRACE | CLOSE_CURLY_BRACE | PIPE | INVERSE | '`' | '\\' | '\u0000'..'\u0020'))* '>'
       ;
   
  
positive.code: LIMIT : ('L'|'l')('I'|'i')('M'|'m')('I'|'i')('T'|'t');
  
  OFFSET : ('O'|'o')('F'|'f')('F'|'f')('S'|'s')('E'|'e')('T'|'t');
  
  OPTIONAL : ('O'|'o')('P'|'p')('T'|'t')('I'|'i')('O'|'o')('N'|'n')('A'|'a')('L'|'l');  
  
  
negative.code: 
  fragment
  ECHAR : '\\' ('t' | 'b' | 'n' | 'r' | 'f' | '\\' | '"' | '\'');
  
  fragment
  PN_CHARS_BASE
  