Lib/fontTools/feaLib/testdata/LigatureCaretByPos.fea

table GDEF {
    LigatureCaretByPos [c_h c_k] 500;

    # The OpenType Feature File specification does not define what should
    # happen when there are multiple LigatureCaretByPos statements for
    # the same glyph. Our behavior matches that of Adobe makeotf v2.0.90.
    # https://github.com/adobe-type-tools/afdko/issues/95
    LigatureCaretByPos o_f_f_i 700 300;
    LigatureCaretByPos o_f_f_i 900;
} GDEF;