Re: Tally marks (was: Re: missing symbol?)

From: Doug Ewell (
Date: Sat Feb 10 2007 - 16:28:54 CST

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    Richard Wordingham <richard dot wordingham at ntlworld dot com> wrote:

    >>> And what about six to ten? I sometimes remember to stack them in
    >>> pairs to simplify the conversion to decimal.
    >> That would be a layout problem.
    > The mark-up being?

    The white space and line breaks necessary to achieve this stacking:

    ||||/ ||||/
    ||||/ ||||/
    ||||/ ||||/

    The simplified conversion to decimal is achieved visually, not through
    any special nature of the tally marks themselves. You could just as
    easily write:

    ||||/ ||||/ ||||/ ||||/ ||||/ ||||/ etc.

    and it would add up the same, but the layout helps.

    > As presented in the code charts, the Aegean numbers under ten are not
    > tally marks. You can't convert THREE to FOUR, FIVE to SIX, or SEVEN
    > to EIGHT.

    They're not the same, but they are comparable. They are essentially
    groups of short marks arranged in a way that facilitates their
    identification as numbers. My point was that the "modern" tally marks,
    grouped into sets of five, have as much legitimacy to encoding as the
    Aegean numbers.

    > On the subject of missing numbers, how is one supposed to write the
    > Roman numeral that would have compatibility decomposition IIII? The
    > obvious compatibility decomposition shows that it can't be a glyph
    > variant of U+2163 ROMAN NUMERAL FOUR - it has compatibility
    > decomposition IV.

    You write it as <0049, 0049, 0049, 0049>. The Roman numerals in the
    U+2100 block that have compatibility decompositions are there only for
    round-tripping with legacy charsets, and should not be used in new text.
    This is a commonly misunderstood point.

    Doug Ewell  *  Fullerton, California, USA  *  RFC 4645  *  UTN #14

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