A vocal piece of Ottoman Turkish music composed in 6/8 meter, or usul semai, or yürük semai. This form and meter (usul in Turkish) is often confused with the completely different Saz Semaisi, an instrumental form consisting of three to four sections, in 10/8 meter, or usul aksak semai (broken semai in Turkish). Semai is one of the most important forms in Ottoman Turkish Sufi music.
The Music of the Ottoman Court - Walter Feldman
Sufism, Music and Society - Swedish Research Institute
Makam - Karl Signell
Meaning in Turkish Musical Culture - Eugenia Popescu-Judetz