+ int Ok = (Lookup->Type == 4) || // This is a mark-to-base attachment
+ ((BaseGlyph->LigatureUid == CurrentGlyph->LigatureUid) && (BaseGlyph->LigatureComponentIndexPlusOne == CurrentGlyph->LigatureComponentIndexPlusOne)) || // This is a mark-to-mark attachment, and both marks belong to the same ligature component
+ ((BaseGlyph->Flags | CurrentGlyph->Flags) & KBTS_GLYPH_FLAG_LIGATURE); // This is a mark-to-mark attachment, and either mark was created by a ligature substitution