Currently, the default OpenType processing mode is the very limited "base" mode, it is supposed to be faster than the more complete "node" mode, but in practice the speed difference is unnoticeable. Since all advanced OpenType features (any thing beyond good old TeX ligaturing) doesn't work in "base" mode, I don't see much point of making it default.
The only place where "base" is required is math, but I think it is reasonable to ask users of OpenType math to set mode to "base", not the other way around. What do you think? Regards, Khaled -- Khaled Hosny Arabic localiser and member of Arabeyes.org team Free font developer
