[ft-devel] old and new kern in gxvalid

[Masatake YAMATO]

I'd like to get your comments.

>From the view of GX/AAT, there are two generations of kern.
`version' field of a generation(old kern) is 16 bit.
That of another generation(new kern) is 32 bit.

New kern is part of GX/AAT specification. Therefore we will handle it
in our gxvalid module. In other hand, old kern is not a part of
GX/AAT. It is more generic in TrueType. About old kern what/how we
should do in gxvalid.

I think there are three ways:

1. Just handle old kern in gxvalid. However, remember old kern is not
   part of GX/AAT.

2. Don't handle old kern in gxvalid. However, if a face including old
   kern is passed, gxvalid may say "kern of this face is broken"
   even if the kern table is valid as an old kern.

3. Handle it in another validator like oldkernvalid module. It is 
   right way from the view of gxvalid developers. However, this approach
   is over-kill.

After discussion with mpsuzuki, we are implementing 1. However, I'd like
to hear your comment.

Regards,
Masatake YAMATO