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