Handling Malayalam "NTA" issue for Lohit2

[pravin.d.s at gmail.com]

Hi All,

    We are working on lohit2[1] project, whose plan is to create standard
and reusable open type tables with additional improvement. Lohit as a
default system fonts in most of the open source distros always follow
standard around language technology. (Font specification, Storage,
Guideline related to Languages)

    Recently we started working on Lohit Malayalam font [2] with some
planned improvement and came across couple of bugs related [3][4] with well
know "NTA" issue introduced during the addition of Atomic chillu characters
in Unicode 5.1

    Now dilemma is number of users already using

*     A. u0D28 + u0D4D + u0D31 for getting NTA character even before
Unicode 5.1 *



*     B. But Unicode from 5.1 onward says (TUS 6.2 chapter 9.9 p 321) use
        u0D7B + u0D4D + u0D31 for getting same "NTA" *
    In my humble opinion here one thing is very clear that Unicode forgot
to add normalization (backward compatibility) for newly added sequence in
(B). Still i have not seen any improvement in it from long time.

    Now dilemma with lohit2 development is

    - Lohit 1 is supporting sequence (A) from long time (even before
Unicode 5.1), so for the backward compatibility lohit2 should support the
same.

    - Since Lohit follows standards, it is important to support sequence
(B) for following Unicode 6.3. But following Unicode 6.3 in this case
clearly invites dual encoding without any normalization rules handy.

    Good documentation on NTA issues is available at [5]

    Presently i am in favour of not supporting Unicode defined sequence (B)
in lohit2 and keep on using (A) which is used in Lohit fonts family from
long time.

    Please let me know your view on it. Is there any chance of getting this
mention in Unicode chapter 9? is there any chance of Normalization rule for
this?


Regards,
Pravin Satpute



1.
http://pravin-s.blogspot.in/2013/08/project-creating-standard-and-reusable.html
2.
http://pravin-s.blogspot.in/2013/12/lohit2-lohit-malayalam-development-plans.html
3. https://bugzilla.redhat.com/show_bug.cgi?id=1016984
4. https://bugzilla.redhat.com/show_bug.cgi?id=1016989
5. http://thottingal.in/documents/Malayalam-NTA.pdf
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