The font for this test case has an AAT Extended Glyph Metamorphosis Table with a single Glyph Insertion Subtable. The glyph M has the SetMark bit set. The glyph A inserts the string INS before the last marked glyph because its MarkedInsertBefore bit is set; whereas B inserts the same after the marked sequence because its MarkedInsertBefore bit is clear. Glyphs C and D perform the same insertion before/after the current glyph. The glyphs P, Q, R, X, Y,Z perform no actions.