置ち換かん文も字じ

noun

replacement character

Computing term for a character used to replace an unknown, unrepresentable, or invalid character, such as U+FFFD.

• Unicodeでは、認にん識しきできない文も字じは置ち換かん文も字じ（U+FFFD）で表ひょう示じされる。

  In Unicode, unrecognized characters are displayed with the replacement character (U+FFFD).