anchor.diff:  
   rootText
       : VERSION
  -    | (MINUS* WORD)+ MINUS*
  +    | WORD+
       | GIBBERISH
       | MINUS
       ;
  
positive.code: // - It may not start with a special character (like '/' )
  fragment B64LetterBase      : [a-zA-Z0-9];
  fragment B64LetterSpecial   : [+?_/];
  fragment B64Letter          : [a-zA-Z0-9+?_/];
  fragment B64FirstChunk
      : B64LetterBase B64Letter B64Letter B64Letter
      ;
  
  fragment B64Chunk
      : B64Letter B64Letter B64Letter B64Letter
  
negative.code:     : (~[0-9+;,{}()\\/ \t:=[\]"-])             // Normal letters
      | '\\x'[0-9a-f][0-9a-f]                    // Hex encoded letters \xab\x12
      ;
  
  WORD
      : MINUS* WORDLetter+ (MINUS+ WORDLetter+ )* MINUS*
      | SPACE MINUS SPACE
      ;
  
  