fonttools/Tests/feaLib/data/GPOS_4.fea

languagesystem DFLT dflt;

markClass [acute grave] <anchor 111 -11> @TOP_MARKS;
markClass macron <anchor 112 -12> @TOP_MARKS;
markClass [cedilla] <anchor 222 22> @BOTTOM_MARKS;
markClass [ogonek] <anchor 333 33> @SIDE_MARKS;

feature test {
    pos base a <anchor 11 1> mark @TOP_MARKS <anchor 12 -1> mark @BOTTOM_MARKS;
    pos base [b c] <anchor 22 -2> mark @BOTTOM_MARKS;
    pos base d <anchor 33 3> mark @SIDE_MARKS;
} test;