PowerAda 12
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(12) The sequence of characters of the value returned by S'Image when some of the graphic characters of S'Wide_Image are not defined in Character.
See 3.5(37).
Any graphic character not defined in Character is represented by the following sequence of characters: <TAB>XXXX, where: <TAB> is Ada.Characters.Latin_1.TAB and XXXX is the hexadecimal value of the wide character.