noun
Computing term for a character that produces a blank space, such as a regular space or tab.
パスワードに間隔文字を含めないでください。
Do not include space characters in the password.
空白 is a more general term for blank space or void, while 間隔文字 specifically refers to a space character in computing contexts.
Compound of 間隔 (interval, spacing) and 文字 (character), literally 'interval character'.