GSUB init, medi, fina and .fea file

["Pablo Rodríguez" <oinos@web.de>]

Hi there,

I have the following OpenType feature archive (intended to use diferent
forms for initial and medial/final beta, theta and phi):

languagesystem DFLT dflt ;

feature init {
    sub uni03D0 by uni03B2 ;
    sub uni03B8 by uni03D1 ;
    sub uni03D5 by uni03C6 ;
} init ;

feature medi {
    sub uni03B2 by uni03D0 ;
    sub uni03D1 by uni03B8 ;
    sub uni03C6 by uni03D5 ;
} medi ;

feature fina {
    sub uni03B2 by uni03D0 ;
    sub uni03D1 by uni03B8 ;
    sub uni03C6 by uni03D5 ;
} fina ;

I use it with this file:

\usemodule[simplefonts]
\definefontfeature[default][default][script=latn,init=yes,medi=yes,fina=yes,featurefile={greeksubs.fea}]
\setmainfont[Theano Didot]
\starttext
βάρβαρος φιλοσοφία θεάσασθαι
\stoptext

But for some strange reason, even with this font I don't get the initial
theta (uni03D1) and middle .

If I change the font, add \agr to the text, change the script or remove
Latin for the default font feature, GSUB no longer work.

As far as I understand, the default rules should be independent from
script, language and font.

What am I missing here or doing simply wrong?

Many thanks for your help,


Pablo
-- 
http://www.oudeis.tk
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