Tests/feaLib/data/spec5f_ii_1.fea

# OpenType Feature File specification, section 5.f.ii, example 1
# "Specifying exceptions to the Chain Sub rule"
# http://www.adobe.com/devnet/opentype/afdko/topic_feature_file_syntax.html

feature test {
    ignore sub f [a e] d';
    ignore sub a d' d;
    sub [a e n] d' by d.alt;
} test;