The Annamese-Muong subfamily is composed of Muong and Vietnamese (also called Annamese). Vietnamese is basically monosyllabic, but it has many words of two or more syllables. It is also tonal, with six tones that frequently help to distinguish homonyms. Vietnamese uses particles but has no prefixes and suffixes. Word order is very important for showing grammatical relationships since there is no inflection. The vocabulary has many loanwords from Chinese. An alphabet based on Roman letters and adapted for Vietnamese, as by adding diacriticals, is generally used today in place of the traditional Chinese-type writing of the past. The classification of Vietnamese is still disputed; some regard it as a Mon-Khmer tongue, others as a Tai (or Thai) language (see Sino-Tibetan languages), and still others as a language unrelated to any other known tongue.