Double-em-dash

The double-em-dash, also known as the long dash and the double-em rule, indicates a missing bit of text, usually an entire word or part of a word, such as "John ——" or "John D——". As its name implies, it is twice as long as an em-dash. It is represented in the proofreading and formatting rounds by four hyphens, thus, "----". In a completed HTML version of an ebook, it is usually represented by two em-dashes, which in many fonts appears as a single, very long dash, thus, "——".