fonttools/Lib/fontTools/feaLib/testdata/GPOS_1.fea

languagesystem DFLT dflt;

@sevenEightNine = [seven eight nine];

feature kern {
    position [one two three] <-80 0 -160 0>;
    position A <1 2 3 4 5 6 7 8>;
    position B <1 2 3 4 5 6 7 8>;
    position four 400;
    position five <-80 0 -160 0>;
    position six -200;
    position @sevenEightNine -100;

    # The AFDKO makeotf tool accepts re-definitions of previously defined
    # single adjustment positionings, provided the re-definition is using
    # the same value.  We replicate this behavior.
    position four 400;
    position four <0 0 400 0>;
    position nine -100;
} kern;

# According to the OpenType Feature File specification section 2.e.iv,
# the following should be interpreted as vertical advance adjustment
# because -100 (a value record format A) appears within a ‘vkrn’ feature.
# However, the AFDKO makeotf tool v2.0.90 (built on Nov 19, 2015) still
# makes it a horizontal advance adjustment.  In our implementation,
# we follow the specification, so we produce different output than makeotf.
# https://github.com/adobe-type-tools/afdko/issues/85
feature vkrn {
    position A -100;
} vkrn;