RE: Hexadecimal digits

From: John Dlugosz (
Date: Tue Jun 08 2010 - 14:43:22 CDT

  • Next message: Robert Abel: "Re: Hexadecimal digits"

    > This last message is certainly more on topic there, it discusses
    > existing characters and their usage in some experimental (mostly

    I think so too.

    > And the 8 characters discussed here (for digits 8..15) are certainly
    > good subjects for a possible proposal for encoding, even if they will
    > certianly not fit in the BMP (they could easily fit in the SMP, and
    > their character properties will certainly not be gc=Nd but gc=No). But
    > I have no opinion if the 8 first digits (for numeric values 0..7)
    > should also be reencoded.

    The keyboard/printer I first learned to type on, in the late 1970s, did not encode a separate glyph for "0"! It didn't have a "1" either, or an "!". This was a mechanical typewriter from earlier in the century, with formed type bars pressing against a ribbon, driven by mechanical force of working each lever.

    In typed documents, 0 or O was determined by context, as was 1 or l. The "!" was formed by overstriking apostrophe with period.

    In the early days of computing, it was obvious to them that they needed to encode digits uniquely, even though we didn't need that before. It means more parts for the printer etc. so there is some commercial pressure against it.

    So, our unique digits are grandfathered in. It was in ASCII and in EBCDIC, so it's in Unicode. Sometime later, assemblers and compilers came along. The writers of these tools had little trouble using context or strict rules to distinguish A-F between their role as digits or numbers. We could do without separate U+0030 and U+0031 today just as well: O is a reserved word in C, identifiers that look like numbers (beginning with O or l and containing only characters that are used to form numeric literals) would be deemed to be parsed as numbers, or use a special mark, or whatever.

    So it's only history that some glyphs used as digits are separate and others (for Computer Science work anyway) are not. In practice, we don't need unique assignments, in general. There are characters that are used in numeric literals and they are a subset of those used for words in general.

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