Input =>  Expect  (    LtoR : ok?) (    RroL : ok? )
    ---        ---        ---   ---        ---   ---  
      I => ......I  ( ......I : Ok ) ( ......I : Ok  )
     IV => .....V.  ( ......I : Not) ( .....V. : Ok  )
      V => .....V.  ( .....V. : Ok ) ( .....V. : Ok  )
     VI => .....VI  ( .....VI : Ok ) ( .....VI : Ok  )
     IX => ....X..  ( ......I : Not) ( ....X.. : Ok  )
      X => ....X..  ( ....X.. : Ok ) ( ....X.. : Ok  )
     XI => ....X.I  ( ....X.I : Ok ) ( ....X.I : Ok  )
    XIV => ....XV.  ( ....X.I : Not) ( ....XV. : Ok  )
     XV => ....XV.  ( ....XV. : Ok ) ( ....XV. : Ok  )
    XVI => ....XVI  ( ....XVI : Ok ) ( ....XVI : Ok  )
    XIX => ....X.I  ( ....X.I : Ok ) ( ....X.. : Not )
      X => ....X..  ( ....X.. : Ok ) ( ....X.. : Ok  )
     XL => ....X..  ( ....X.. : Ok ) ( ...L... : Not )
     LX => ...LX..  ( ...LX.. : Ok ) ( ...LX.. : Ok  )
     XC => ....X..  ( ....X.. : Ok ) ( ..C.... : Not )
  CLXIX => ..CLX.I  ( ..CLX.I : Ok ) ( ..CLX.. : Not )
 CDXLVI => .D..XVI  ( ..C.XVI : Not) ( .D.L.VI : Not )
MCMXCVI => M.C.XVI  ( M.C.XVI : Ok ) ( M.C..VI : Not )
  MDCLI => MDCL..I  ( MDCL..I : Ok ) ( MDCL..I : Ok  )