noun
hidden character; non-printable character
Computing term for characters that do not produce a visible mark, such as control codes or zero-width characters.
テキストファイルに非表示文字が含まれていると、表示が乱れることがある。
If a text file contains hidden characters, the display may become garbled.
制御文字 specifically refers to control characters (e.g., line feed, carriage return), while 非表示文字 is a broader term for any character that is not visually displayed.
Compound of 非表示 (non-display) and 文字 (character). The exact derivation is uncertain, but the term is a straightforward technical coinage.