That decisions of this sort must have caused some headache even to contemporary conductors may be guessed from Michael Praetorius’ practical editing of another item of the Monteverdi Vespers, ‘Ave maris Stella.’ These choral variations ‘a 8’ on a plain-chant melody are written for eight-part double choir, Basso continuo, with intersticial ritornelli, scored for an unspecified orchestra ‘a5’. There are variations for semi-chorus and for soloists. In the very end (‘Sit laus’) the composer unites both semi-choirs (without the usually preceding ritornelli).