No, chords are rotational intervals addition, dependant to the type of lentgh. I've used for that my function: add-interval-if-length revised by Torsten. Here it is:   ;;; ============================================== ;;; UTILITY FUNCTIONS ;;; (defun add-interval-if-length-aux (omn &key (test #'>) (length-val 1/8) (interval-list '(4 3 4 7 4 3 5 4 7 3))) (let ((s-events (single-events omn))) (loop for e in s-events for i in (gen-trim (length s-events)