The double hyphen (⸗) is a punctuation mark that consists of two parallel hyphens. It is not to be confused with two consecutive hyphens (--), which usually represent an em dash (—) on devices which do not have a dedicated em dash glyph. In order to avoid its being confused with the equals sign (=), which is a mathematical symbol indicating equality, the double hyphen is often rotated slightly counter-clockwise.

Usage

The double hyphen is used for several different throughout the world:

• Some typefaces, such as Fraktur, use the double hyphen as a graphical variant of the single hyphen.
• It may be also used for artistic or commercial purposes to achieve a distinctive visual effect. For example, the name of the Waldorf-Astoria Hotel is officially written with a double hyphen.
• In Merriam-Webster dictionaries if a word is divided at the end of the line, and the division-point happens to be a hyphen, it is replaced with a double hyphen to graphically indicate that the divided word is normally hyphenated, for example cross⸗
  country.
• It is used as a distinct punctuation mark by Coptic language scholars.

Unicode

When the double hyphen is used as a functionally equivalent graphical variant of the single hyphen, it is represented in Unicode as a normal hyphen.

When used as a punctuation mark distinct from the single hyphen, the double hyphen is represented in Unicode by two different code points:

Punctuation | Typography