This Urtext edition takes into account all the sources including the old and the new complete editions whose relationship is clearly explained in a stemma. In several passages the renowned Beethoven specialist Barry Cooper has arrived at variant readings, such as in the “Sanctus”, where the choir enters instead of the soloists, rather than coming in at “Pleni sunt coeli”. No less worthy of mention is the addition of the soloists to the choir in most of the “Credo”. These matters and many other editorial decisions are documented in the detailed Critical Commentary (Eng).