Another similar system not adopted for official use in Bulgaria is that of A. Danchev, M. Holman, E. Dimova and M. Savova, which transliterates the Cyrillic letters У and Ъ by "OU" and "U" respectively, while the Streamlined System uses "U" and "A" for this purpose. Furthermore, the latter system transliterates the digraphs АЙ•ай, ЕЙ•ей, ОЙ•ой and УЙ•уй by AI•ai, EI•ei, OI•oi and OUI•oui instead of AY•ay, EY•ey, OY•oy and UY•uy respectively.