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> ISO 8601 uses a hyphen character (in Unicode, U+2010 HYPHEN "‐") and minus character (in Unicode, U+2212 MINUS "−"). When using character sets which don't hav

> ISO 8601 uses a hyphen character (in Unicode, U+2010 HYPHEN "‐") and minus character (in Unicode, U+2212 MINUS "−"). When using character sets which don't have these characters a hyphen-minus character (in Unicode, U+2D HYPHEN-MINUS "-") should be used instead. This is incorrect. What ISO 8601 actually specifies is that, if the target character set is based on ISO/IEC 646 (which definitely includes Unicode), then a hyphen-minus character should be used for both cases. There is a slight ambiguity here (e.g. what if some charset contains most but not all characters in 646?) but in the case of Unicode the interpretation is clear. I believe this is a roundabout way to specify the canonical mapping for 646 and guarantee the compatibility with other charsets based on 646.

ijmacd 3y ago
That's very interesting. The relevant paragraph from the standard is in ISO 8601-1:2019 §3.2.1: > All characters used in date and time expressions and representations are part of the ISO/IEC 646 repertoire, except for “hyphen”, “minus” and “plus-minus”. In an environment where use is made of a character repertoire based on ISO/IEC 646, “hyphen” and “minus” should be both mapped onto “hyphen-minus”. And as you correctly state, Unicode is based on ISO 8859 which is based on ISO 646. So it would seem the intention really is to use U+2D hyphen-minus when Unicode is the character set.
deleted 3y ago
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