5 ms·

Not really related but do we really need 4 different unicode symbols for the same glyph? It's not even like it represents different things - whats the differenc

Not really related but do we really need 4 different unicode symbols for the same glyph? It's not even like it represents different things - whats the difference between a tricolon and triple colon or the difference between a vertical ellipsis and a presentation form of vertical horizontal ellipsis (which is really a vertical ellipsis described with twice as many words?) " ⁝ - U+205D tricolon ⋮ - U+22EE vertical ellipsis ⫶ - U+2AF6 triple colon operator ︙- U+FE19 presentation form for vertical horizontal ellipsis "

teddyh 7y ago
The usual reason for Unicode symbol redundancy is round-trip encoding compatibility.
- tempguy9999 7y ago
  I don't understand, could you elaborate briefly?
  - rangibaby 7y ago
    I think Unicode tries to avoid this: encoding A,B,C visually identical character → Unicode One True Character → garbage in encoding A,B,C
jbverschoor 7y ago
The semantics are different.
- Illniyar 7y ago
  What is the semantic difference between a "tricolon" and a "triple colon operator" m
  - maweki 7y ago
    one is a mathematical operator, the other is not
    - Illniyar 7y ago
      Any idea where is a triple colon operator used actually? I can find Vertical Ellipsis in matrices to denote continuation but nothing about using the glyph as an operator
  - goto11 7y ago
    Tricolon is punctuation (like the dash) while triple colon operator is a mathematical symbol (like a minus).
  - eesmith 7y ago
    Since I had no clue, and was curious, I tried to find out. "Tricolon" shares a name with a far more common use as a rhetorical technique, making it hard to find details. I tracked down the Unicode proposal for 'Epidaurean acrophonic symbol three' at http://www.unicode.org/L2/L2003/03075r2-tlg-numeric.pdf http://www.unicode.org/L2/L2003/03075r2-tlg-numeric.pdf . > This proposal contains 52 Greek Acrophonic (numerical, non-alphabetic) characters. Acrophonic numerals are found primarily in ancient Greek inscriptions in Athens and other city states. ... The proposal includes the characters needed for the encoding of the Attic acrophonic system—namely characters used in Athens and the surrounding area (Attica)—and non-Attic characters which cannot be considered as glyph variants of Attic. It has the comment "Note: Accepted by UTC (2003-11-7) as part of extended Greek punctuation. Design to match 00B7. Example: IG IV.316". That's Ancient Greek. I tried, but failed, to find the example from Inscriptiones Graecae IV.316. I couldn't figure out the reason for why the triple colon operator was added, other than the comment in the Unicode database that it's used in "logic". There's a 2002 mention of it at https://unicode.org/L2/L2002/02174-tr25-5.pdf https://unicode.org/L2/L2002/02174-tr25-5.pdf .
    - goto11 7y ago
      Well the article itself shows the use of tricolon punctuation in bibliographies. Some comments on the page elaborate on that point.
goto11 7y ago
Unicode encodes symbols rather than glyphs. That is why there are different code points for say latin o and greek omicron even though they look the same. It also distinguishes between punctuation symbols and mathematical operators, like between dash and minus, even though they look similar. As for the "presentation forms" they are not semantically different and are mostly a compatibility thing: A: Presentation forms are ligatures or glyph variants that are normally not encoded but are forms that show up during presentation of text, normally selected automatically by the layout software. A typical example are the positional forms for Arabic letters. These don't need to be encoded, because the layout software determines the correct form from context. For historical reasons, a substantial number of presentation forms were encoded in Unicode as compatibility characters, because legacy software or data included them. Unicode FAQ, https://unicode.org/faq/ligature_digraph.html#Pf1 https://unicode.org/faq/ligature_digraph.html#Pf1
- nyuszika7h 7y ago
  And yet, they do not have a mathematical italic "h" letter, using the reasoning that the Planck constant (ℎ) already exists. But this character looks out of place compared to the rest of the italic letters in many fonts.
  - K0SM0S 7y ago
    Oh thank you for pointing that out! There is also a lack of indices and exponents, among the most importants (can't remember but letters like i, x or n).
    - YeGoblynQueenne 7y ago
      You need a font that supports those and superscript-x is a modifier, rather than a subscript, but: aⁱ U+0271 Superscript Latin Small Letter I aˣ U+02e3 Modifier Letter Small X aⁿ U+207f Superscript Latin Small Letter N aᵢ U+1d62 Latin Subscript Latin Small Letter I aₓ U+2093 Latin Subscript Latin Small Letter X aₙ U+2099 Latin Subscript Latin Small Letter N I use DejaVu Sans Mono that is free and has some coverage, though it's missing the most inopportune ones. But you're right that there are many missing, either from the sub- and supescript ranges or from modifiers (or both). Edit: there's a page on wikipedia with a very complete list of unicode sub- and super-scripts _and other characters that can be used as such_: https://en.wikipedia.org/wiki/Unicode_subscripts_and_superscripts https://en.wikipedia.org/wiki/Unicode_subscripts_and_supersc... But, again, you need the right fonts.
atoav 7y ago
You could ask the same thing about hypen, dash and minus sign, but they are different in their meaning and as someone who layouts texts I might want to style them differently from each other
- tomcooks 7y ago
  Hyphen, dash, and minus do not look the same, nor have the same use.
  - zaarn 7y ago
    I bet the average person on the street would tell you that these are the same and they never thought about hyphen and minus being different. For them all three look like a dash.
  - reaperducer 7y ago
    Hyphen, dash, and minus do not look the same Depends on your font. Not every font or display has the resolution available to make that distinction.
Izkata 7y ago
That last one might be "..." for vertical monospace text, like traditional Japanese. Not sure though as when I highlight it, it doesn't look wide enough.

teddyh 7y ago

The usual reason for Unicode symbol redundancy is round-trip encoding compatibility.

tempguy9999 7y ago
I don't understand, could you elaborate briefly?
- rangibaby 7y ago
  I think Unicode tries to avoid this: encoding A,B,C visually identical character → Unicode One True Character → garbage in encoding A,B,C

jbverschoor 7y ago

The semantics are different.

Illniyar 7y ago
What is the semantic difference between a "tricolon" and a "triple colon operator" m
- maweki 7y ago
  one is a mathematical operator, the other is not
  - Illniyar 7y ago
    Any idea where is a triple colon operator used actually? I can find Vertical Ellipsis in matrices to denote continuation but nothing about using the glyph as an operator
- goto11 7y ago
  Tricolon is punctuation (like the dash) while triple colon operator is a mathematical symbol (like a minus).
- eesmith 7y ago
  Since I had no clue, and was curious, I tried to find out. "Tricolon" shares a name with a far more common use as a rhetorical technique, making it hard to find details. I tracked down the Unicode proposal for 'Epidaurean acrophonic symbol three' at http://www.unicode.org/L2/L2003/03075r2-tlg-numeric.pdf http://www.unicode.org/L2/L2003/03075r2-tlg-numeric.pdf . > This proposal contains 52 Greek Acrophonic (numerical, non-alphabetic) characters. Acrophonic numerals are found primarily in ancient Greek inscriptions in Athens and other city states. ... The proposal includes the characters needed for the encoding of the Attic acrophonic system—namely characters used in Athens and the surrounding area (Attica)—and non-Attic characters which cannot be considered as glyph variants of Attic. It has the comment "Note: Accepted by UTC (2003-11-7) as part of extended Greek punctuation. Design to match 00B7. Example: IG IV.316". That's Ancient Greek. I tried, but failed, to find the example from Inscriptiones Graecae IV.316. I couldn't figure out the reason for why the triple colon operator was added, other than the comment in the Unicode database that it's used in "logic". There's a 2002 mention of it at https://unicode.org/L2/L2002/02174-tr25-5.pdf https://unicode.org/L2/L2002/02174-tr25-5.pdf .
  - goto11 7y ago
    Well the article itself shows the use of tricolon punctuation in bibliographies. Some comments on the page elaborate on that point.

goto11 7y ago

Unicode encodes symbols rather than glyphs. That is why there are different code points for say latin o and greek omicron even though they look the same. It also distinguishes between punctuation symbols and mathematical operators, like between dash and minus, even though they look similar. As for the "presentation forms" they are not semantically different and are mostly a compatibility thing: A: Presentation forms are ligatures or glyph variants that are normally not encoded but are forms that show up during presentation of text, normally selected automatically by the layout software. A typical example are the positional forms for Arabic letters. These don't need to be encoded, because the layout software determines the correct form from context. For historical reasons, a substantial number of presentation forms were encoded in Unicode as compatibility characters, because legacy software or data included them. Unicode FAQ, https://unicode.org/faq/ligature_digraph.html#Pf1 https://unicode.org/faq/ligature_digraph.html#Pf1

nyuszika7h 7y ago
And yet, they do not have a mathematical italic "h" letter, using the reasoning that the Planck constant (ℎ) already exists. But this character looks out of place compared to the rest of the italic letters in many fonts.
- K0SM0S 7y ago
  Oh thank you for pointing that out! There is also a lack of indices and exponents, among the most importants (can't remember but letters like i, x or n).
  - YeGoblynQueenne 7y ago
    You need a font that supports those and superscript-x is a modifier, rather than a subscript, but: aⁱ U+0271 Superscript Latin Small Letter I aˣ U+02e3 Modifier Letter Small X aⁿ U+207f Superscript Latin Small Letter N aᵢ U+1d62 Latin Subscript Latin Small Letter I aₓ U+2093 Latin Subscript Latin Small Letter X aₙ U+2099 Latin Subscript Latin Small Letter N I use DejaVu Sans Mono that is free and has some coverage, though it's missing the most inopportune ones. But you're right that there are many missing, either from the sub- and supescript ranges or from modifiers (or both). Edit: there's a page on wikipedia with a very complete list of unicode sub- and super-scripts _and other characters that can be used as such_: https://en.wikipedia.org/wiki/Unicode_subscripts_and_superscripts https://en.wikipedia.org/wiki/Unicode_subscripts_and_supersc... But, again, you need the right fonts.

atoav 7y ago

You could ask the same thing about hypen, dash and minus sign, but they are different in their meaning and as someone who layouts texts I might want to style them differently from each other

tomcooks 7y ago
Hyphen, dash, and minus do not look the same, nor have the same use.
- zaarn 7y ago
  I bet the average person on the street would tell you that these are the same and they never thought about hyphen and minus being different. For them all three look like a dash.
- reaperducer 7y ago
  Hyphen, dash, and minus do not look the same Depends on your font. Not every font or display has the resolution available to make that distinction.

Izkata 7y ago

That last one might be "..." for vertical monospace text, like traditional Japanese. Not sure though as when I highlight it, it doesn't look wide enough.