It is based on the rules of the Deutsche Morgenländische Gesellschaft (DMG) as modified by the International Orientalist Congress 1935 in Rome.
Its acceptance relies less on its official status than on its elegance (one sign for each Arabic letter) and the Geschichte der arabischen Literatur manuscript catalogue of Carl Brockelmann and the dictionary of Hans Wehr.
Along with rules for the Arabic language, it also includes transliteration standards for Ottoman Turkish, Persian, Kurdish, Urdu, and Pashto.
The letter (ﺓ) tāʾ marbūṭah is transliterated as word-final -h normally, or -t in a word in the construct state.
Hamzah has many variants, أ إ ء ئ ؤ; depending on its position, all of them are transliterated as ⟨ʾ⟩.