In a recent entry of Raymond Chen’s blog “The Old New Thing”, he explains how the time format was changed in Windows 8 to use the Unicode character (U+2236 RATIO) instead of : (U+003A COLON):

  • old: 7:00
  • new: 7∶00

The post includes a number of issues that had to be addressed with this change. For example, U+2236 is not in category CS (“common number separator”), leading to incorrect behavior in right-to-left layouts.

Given this, I wondered whether the change was sensible in the first place. This seems like a presentation issue at the level of glyphs in fonts rather than something which called for a different representation of the data. Commenter Andreas Rejbrand exactly summarizes my doubts:

Andreas Rejbrand
September 13, 2018 at 11:59 am

This is interesting. ∶ is U+2236: RATIO in block “Mathematical operators”, which I would guess would be used to indicate ratios, or fractions, like 1∶1000.

Indeed, the official Unicode document [1] says, “preferred to 003A : [the ASCII colon, my remark] for denotation of division or scale in mathematical use”.

Hence, this doesn’t feel like elegant typography to me; it feels more like semantic misuse of Unicode characters, a bit like using the masculine ordinal indicator (º) instead of the degree sign (°, extremely common mistake).

[1] https://www.unicode.org/charts/PDF/U2200.pdf

Is this a valid use of the character U+2236 RATIO?

Note: I hope this question is appropriate here. I was directed here from Stack Overflow.

  • 2
    Hi, welcome to UXSE. My guess would be no. time (like 17:40) is not a ratio like your screen ratio (like 16:9) what the unicode character in question suppossedly is for. – Martijn Vissers Nov 20 '18 at 13:46

Date/time formatting follows a series of conventions that are globally stated and standardized. You can find the specific time formatting for every locale in the CLDR (Unicode Common Locale Data Repository). So, time formatting is not something you would be speculating about: there is a strict series of rules you should follow to comply with the globally recognized standards.

That said, on the "Date & Time chart" you can find the Hour-minutes standard formatting rules.

The most common one is the one you wrote about, and it is written using COLON (0x3A) as the time separator character.

Not using the standard format could lead to downsides in a matter of accessibility, automatic parsing, weird behavior with limited fonts and unpredictable others.

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