anchor.diff:        else
           let sr  = r <<< 4
           let   c = x.ch
  -        if    c >= '0' && c <= '9'  then x.adv () ; x.tryParse_UnicodeChar (n - 1, sr + (int c - int '0'))
  +        if    isDigit c             then x.adv () ; x.tryParse_UnicodeChar (n - 1, sr + (int c - int '0'))
           elif  c >= 'A' && c <= 'F'  then x.adv () ; x.tryParse_UnicodeChar (n - 1, sr + (int c - int 'A' + 10))
           elif  c >= 'a' && c <= 'f'  then x.adv () ; x.tryParse_UnicodeChar (n - 1, sr + (int c - int 'a' + 10))
           else
  
positive.code:         result && x.consume_WhiteSpace ()
  
      member x.tryParse_Eos () : bool =
        if x.eos then
          true
        else
          v.Expected (pos, Tokens.EOS)
          false
  
    [<AbstractClass>]
    [<NoEquality>]
  
negative.code:         let spos        = pos
          let mutable uf  = 0.0
          if x.tryParse_UInt (true, &uf) then
            r <- uf * (pow10 (spos - pos))
            true
          else
            false
  