noun
dedicated data character
Technical computing term for a character reserved for data transmission or control purposes, not for general text.
このプロトコルでは、データ専用文字を使って制御情報を送ります。
In this protocol, dedicated data characters are used to send control information.
Compound of データ (data) + 専用 (exclusive use) + 文字 (character). A straightforward technical term with no special historical derivation.