fonttools/Tests/feaLib/data/spec5fi3.fea

# OpenType Feature File specification, section 5.f.i, example 3
# "Specifying a Chain Sub rule and marking sub-runs"
# http://www.adobe.com/devnet/opentype/afdko/topic_feature_file_syntax.html

languagesystem latn dflt;

feature test {
    sub [A-Z] [A.sc-Z.sc]' by [a-z];
} test;