In Vietnam, people like to use VNI font in the south and ABC (TCVN) font in the north because the beauty of these fonts.
Yep. That's true. That's also why I'm working on converting some of these fonts to Unicode (even if for some of them it's totally illegal to do so...) to keep using the old beautiful fonts, but the right way (Unicode encoding).
So if you want to convert, you must convert it again & again when you receive a document from Vietnamese person.
Exact. That's why I did an OO.o extension which allows you to do it only with one clic and no question, the easiest way possible for non-technical users.
Still, it becomes very rare to find a document using old encoding, I know that because now I have hard time to find one to check my tool (or even people to try it for me)...
I am using OO.o, I have no problem when using VNI/ACB font.
VNI is using compositing characters method, so you will have problem when exchanging data (text) between this old encoding and other ones (especially Unicode in canonical form).
I repeat: there is multiple technical reasons for not wanting to keep the old encodings and switching definitively to Unicode.
These are alternative fonts beside Unicode fonts but old fonts or obseleted font as you said.
These are wrongly encoded fonts which were a good solution at that time, but is now a brake to technical progress in Vietnam.
Same here! But with 10 years of experience in managing Vietnam encodings and fonts to let everything working well on GNU/Linux. ;-)