From: Andrew C. West (
Date: Fri Oct 24 2003 - 03:32:35 CST

On Thu, 23 Oct 2003 13:05:05 -0700, Peter Lofting wrote:
> The representation of slashed digits are problematic for two reasons.
> (1) The notation is that a slash indicates half of the value. This is
> different to the "less a half" interpretation Andrew describes, which
> would only be true for the digit "1".

I was pretty sure that the slash *normally* indicated "half less than",
corresponding to the way in which fractions are represented in written Tibetan
(phyed + integer = half less than integer). Certainly, the only printed example
of a half digit that I know of (the 1933 7 1/2 skar Tibetan postage stamp) is
written as slashed eight (i.e. phyed brgyad = half less than eight).

If the slash denoted "half of the value" then slashed even numbers would be
integers (e.g. slashed 8 = 4), and what would the point of that be ?

The problem is what slashed zero means. Following the "half less than" rule
UnicodeData.txt assigns it a value of "-1/2", but a single negative half number
seems very improbable to me (it would not be much use without negative half
digits through to -9 1/2 ... as well as negative integers, and even then who's
using negative half digits ??). On the other hand the value of 9 1/2 (or 19/2)
is needed to complete the series of half digits between zero and ten given by
slashed 1 through slashed 9 (1/2 through 17/2). It therefore seems logical to me
that slashed zero in fact represents "ten less a half".

As Peter says, it would be really useful if the people responsible for the
encoding of these half digits could (even at this late stage) provide some
concrete examples of their usage, and clear indication of their numeric value.


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