fonttools/Lib/fontTools/feaLib/testdata/spec6e.fea

languagesystem DFLT dflt;

markClass sukun <anchor 261 488> @TOP_MARKS;
markClass kasratan <anchor 346 -98> @BOTTOM_MARKS;

feature test {
    pos ligature lam_meem_jeem <anchor 625 1800> mark @TOP_MARKS    # mark above lam
        ligComponent <anchor 376 -368> mark @BOTTOM_MARKS    # mark below meem
        ligComponent <anchor NULL>;   # jeem has no marks
} test;