noun
inert function character
Computing term for a character that has no functional effect in a given context, such as a no-op control character.
このプロトコルでは、不活性機能文字は無視される。
In this protocol, inert function characters are ignored.
Compound of 不活性 (inert, inactive) + 機能 (function) + 文字 (character). The exact derivation is uncertain; it is a technical term likely coined in computing contexts.