In Latin script, the double hyphen ⹀ is a punctuation mark that consists of two parallel hyphens. It was a development of the earlier double oblique hyphen ⸗, which developed from a Central European variant of the virgule slash, originally a form of scratch comma. Similar marks (see below) are used in other scripts.
In order to avoid it being confused with the equals sign =, the double hyphen is often shown as a double oblique hyphen in modern typography. The double hyphen is also not to be confused with two consecutive hyphens (--), which are often used to represent an em dash — or en dash – due to the limitations of typewriters and keyboards that do not have distinct hyphen and dash keys.
The double hyphen is used for several different purposes throughout the world:
When the double hyphen is used as a functionally equivalent graphical variant (allograph) of the single hyphen, it has the same Unicode code point as a conventional hyphen (since how it is displayed/printed is a font choice on that occasion).
Other forms of double hyphen are given unique codepoints in Unicode:
Name | Glyph | Code point | Purpose |
---|---|---|---|
CANADIAN SYLLABICS HYPHEN | ᐀ | U+1400
|
Canadian Aboriginal Syllabics to distinguish a hyphen from U+1428 CANADIAN SYLLABICS FINAL SHORT HORIZONTAL STROKE ( ᐨ )
|
DOUBLE OBLIQUE HYPHEN | ⸗ | U+2E17
|
Coptic and ancient Near Eastern language scholarship |
DOUBLE HYPHEN | ⹀ | U+2E40
|
Generic (non-Asian) double hyphen |
KATAKANA-HIRAGANA DOUBLE HYPHEN | ゠ | U+30A0
|
Japanese and orthography (in Katakana or Hiragana script) |
MODIFIER LETTER SHORT EQUALS SIGN | ꞊ | U+A78A
|
Used as a tone letter and also to mark clitics in interlinear glossing |