music is the maqam (pl. maqamat), which looks like the mode, but is not quite the same. The tonic note, dominant note, and ending note (unless modulation occurs) are generally determined by the maqam used. Arabic maqam theory as described in literature over the ages names between 90 and 110 maqams, that are grouped into larger categories known as fasilah. Fasilah are groupings of maqams whose first four primary pitches are shared in common. Ajnas The maqam consists of at least two ajnas, or scale segments. Ajnas is the plural form of jins, which in Arabic comes from the Latin word genus, meaning "type". In practice, a jins is either a trichord (three notes), a tetrachord (four notes), or a pentachord (five notes). A maqam usually covers only one octave (usually two ajnas), but can cover more. Like the melodic minor scale, some maqamat use different ajnas when descending and ascending. Due to continuous innovation and the emergence of new ajnas, and because most music scholars have not reached consensus on the subject, a solid figure for the total number of ajnas in use is uncertain. In practice, however, most musicians would agree there are at least eight major ajnas: rast, bayat, sikah, hijaz, saba, kurd, nahawand, and ajam, and commonly used variants such as nakriz, athar kurd, sikah beladi, saba zamzama. For example, Mukhalif is a rare jins (in the Sikah) family used almost exclusively in Iraq, and it is not used in combination with other ajnas. Microtones in Arabic music Unlike the tradition of Western music, Arabic music contains microtones, which are notes that lie between notes in the Western chromatic scale. While notes in the chromatic scale are separated by semitones (or half steps), notes in Arabic music can be separated by quarter tones. In some treatments of theory, the quarter tone scale or all twenty four tones should exist, but according to Yūsuf Shawqī (1969), fewer tones are used in practice. Additionally, in 1932, at the Cairo Congress of Arab Music held in Cairo, Egypt—and attended by such Western luminaries as Béla Bartók and Henry George Farmer—experiments were done that determined conclusively that the notes in actual use differ substantially from an even-tempered 24-tone scale. Furthermore, the intonation of many of those notes differ slightly from region to region (Egypt, Turkey, Syria, Iraq). Regional scales As a result of these findings, the following recommendation was issued: