fonttools/Tests/feaLib/data/GPOS_5.fea

markClass [acute grave] <anchor 500 700> @TOP_MARKS;
markClass macron <anchor 500 750> @TOP_MARKS;
markClass [cedilla] <anchor 500 -10> @BOTTOM_MARKS;
markClass [ogonek] <anchor 800 -10> @OGONEK;

feature test {

    pos ligature [c_t s_t] <anchor 500 800> mark @TOP_MARKS <anchor 500 -200> mark @BOTTOM_MARKS
        ligComponent <anchor 1500 800> mark @TOP_MARKS <anchor 1500 -200> mark @BOTTOM_MARKS <anchor 1550 0> mark @OGONEK;

    pos ligature f_l <anchor 300 800> mark @TOP_MARKS <anchor 300 -200> mark @BOTTOM_MARKS
        ligComponent <anchor 600 800> mark @TOP_MARKS <anchor 600 -200> mark @BOTTOM_MARKS;

    pos ligature [f_f_l] <anchor 300 800> mark @TOP_MARKS <anchor 300 -200> mark @BOTTOM_MARKS
        ligComponent <anchor 600 800> mark @TOP_MARKS <anchor 600 -200> mark @BOTTOM_MARKS
        ligComponent <anchor 900 800> mark @TOP_MARKS <anchor 900 -200> mark @BOTTOM_MARKS;

} test;