Romanization of Bulgarian
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.