Romanization of Bulgarian
The Streamlined System is similar to the old 1952 BGN/PCGN System for the Romanization of Bulgarian, which had been official in the USA and the United Kingdom until 2013.  The latter however transliterates the Cyrillic letters Х, Ь and Ъ as KH, ’ (apostrophe) and Ŭ, while the former uses H, Y and A instead.