From: Shriramana Sharma (email@example.com)
Date: Mon Apr 05 2010 - 09:24:24 CDT
On 2010-Apr-05 01:58, karl williamson wrote:
> Tamil's digits are not positional according to Richard Gillam. They
> have General category of Nd. Could this be used to cause a naive program
> to calculate an incorrect value of an input number, such that mention of
> this possibility would be warranted in TR36?
Have you read: http://www.unicode.org/notes/tn21/ ? It is hinted (though
not perhaps very explicitly said) that today the positional system is
indeed used. Therefore I (a native Tamil speaker and writer) do not
think that today we would expect applications to *commonly* support the
old numeral system.
In any case, non-positional evaluation of numbers should only be
performed by an application if it encounters the characters ௰ ௱ and ௲. A
number which does not use these characters can safely be processed as
positional. A number which uses them, on the other hand, will have to be
checked for being properly formatted, i.e. properly composed, since in
the non-positional system digits like ௧ ௨ etc would never be seen
adjacent to each other without being punctuated by one of the three
characters ௰ ௱ and ௲. Therefore any number containing one of ௰ ௱ and ௲
but also containing any two normal digits ௧ ௨ etc adjacent to each other
is badly formatted and hence has no (defined) value.
Therefore there is a clear distinction between the two systems, and
while the same numerical value can be represented by two different
strings of characters, one for each system, the same string cannot
represent two different numbers. These systems are self-exclusive. I
mean to say that they both naturally exclude the simultaneous use of the
other system in the same number. Therefore I think that there is little
scope for security problems here.
-- Shriramana Sharma
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