... Unlike the previous digital-only Messages, Arecibo-1974 and Evpatoria-1999, the TAM has complex, three-section structure with different forms of information. Section 1 represents coherent sounding radio signal with slow Doppler wavelength tuning to imitate transmission from Sun's center. ... Section 2 is an analog information and represents musical melodies, performed on the Theremin. ... There were seven musical compositions in the 1st Theremin Concert for Aliens. ...