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It seem to me that this is something best handled with tag characters, like ¤XBT + (U+E007F) = ₿ (where the letters are from the tag block, U+E00xx). This mirro

It seem to me that this is something best handled with tag characters, like ¤XBT + (U+E007F) = ₿ (where the letters are from the tag block, U+E00xx). This mirrors one of the two systems for rendering national flags[0], just with a different starting codepoint, and can easily accommodate all the ISO 4217 currency codes and common unofficial extensions. If a system doesn't know how to render a particular glyph it can just fall back to showing the Roman capital letters. The downside of this approach is size: each tag codepoint (including the end marker) requires four bytes in UTF-8, plus two for ¤, so the sequence above is 18 bytes long. [0] https://en.wikipedia.org/wiki/Tags_(Unicode_block)#Current_use https://en.wikipedia.org/wiki/Tags_(Unicode_block)#Current_u...

lifthrasiir 5y ago
That sounds interesting, but modern currency symbols are already fast-tracked anyway---they almost always get assigned in the next version of Unicode---and more than one currency symbols for given ISO 4217 code can exist so I don't think it would work.
- nybble41 5y ago
  > modern currency symbols are already fast-tracked anyway For national currencies, perhaps. New national currencies aren't introduced all that often, and there is a lot of pressure to support them quickly as their use is often mandatory for anyone living in that jurisdiction. For new private currencies, including crypto-currencies, we don't see quite the same eagerness—the observation that new crypto-currencies were more likely to reuse existing Unicode symbols than invent new ones was a consideration in getting the Bitcoin symbol adopted, as they didn't want to open up the floodgates to large numbers of new currency symbols. The tag-based system offers a compromise. > and more than one currency symbols for given ISO 4217 code can exist so I don't think it would work That is a bit of a problem, but it could be handled with the variant selector codepoints, for example ¤MOP = MOP$, ¤MOP(VS1) = 圓, and ¤MOP(VS2) = 元, if the symbols have the same meaning. To save some space the VS could replace the end codepoint. For fractional units there could be a different prefix such as ¢ for 1/100 or ₥ for 1/1000 in place of the ¤, or incorporating one of the Unicode fraction codepoints for other ratios up to ⅞ (or ⅑ or ⅒). These would be rendered verbatim in the fallback version, like ¢USD.

lifthrasiir 5y ago

That sounds interesting, but modern currency symbols are already fast-tracked anyway---they almost always get assigned in the next version of Unicode---and more than one currency symbols for given ISO 4217 code can exist so I don't think it would work.

nybble41 5y ago
> modern currency symbols are already fast-tracked anyway For national currencies, perhaps. New national currencies aren't introduced all that often, and there is a lot of pressure to support them quickly as their use is often mandatory for anyone living in that jurisdiction. For new private currencies, including crypto-currencies, we don't see quite the same eagerness—the observation that new crypto-currencies were more likely to reuse existing Unicode symbols than invent new ones was a consideration in getting the Bitcoin symbol adopted, as they didn't want to open up the floodgates to large numbers of new currency symbols. The tag-based system offers a compromise. > and more than one currency symbols for given ISO 4217 code can exist so I don't think it would work That is a bit of a problem, but it could be handled with the variant selector codepoints, for example ¤MOP = MOP$, ¤MOP(VS1) = 圓, and ¤MOP(VS2) = 元, if the symbols have the same meaning. To save some space the VS could replace the end codepoint. For fractional units there could be a different prefix such as ¢ for 1/100 or ₥ for 1/1000 in place of the ¤, or incorporating one of the Unicode fraction codepoints for other ratios up to ⅞ (or ⅑ or ⅒). These would be rendered verbatim in the fallback version, like ¢USD.