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

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:

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

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