Chahargah (Calligraphy No. 19) for string quartet with optional contrabass may be performed using the Persian Traditional Tuning System. A detailed chart to set the interval measurements is included with the music. Chahargah (Calligraphy No. 19) is part of Reza Vali's Calligraphies series, an ongoing cycle of works based on the Persian modal system, the Dastgah, which he has been composing since 2000. Versions for string quartet and 10 solo string instruments are available from the publisher.