In recent years a number of scholars have devoted increasing attention to the structure of music prints in the sixteenth century. The reasons why composers or publishers decided on the order of the individual items in a collection are not always obvious. A set of Magnificats would of course appear in the order of the eight reciting tones that served as their cantus firmi, and some collections of motets were organized according to liturgical considerations, but the texts themselves, either Latin or vernacular, did not often imply a specific order when they were grouped in a publication. Harold Powers has articulated most clearly how traits of the music itself came to be used as an organizing factor. He observed that early sixteenth-century collections such as those of Petrucci have “no discernible musical basis for their arrangement,” while later in the century compositions came to be grouped according to three criteria: (1) whether cantus durus or cantus mollis governed, that is, whether the signature contained no flat or one; (2) whether the range was relatively lower or higher as shown by one of the two standard combinations of clefs, the so-called chiavette or “high” clefs and the normal or “low” clefs; (3) the final, expressed as the lowest note in the last sonority (or in modern terms, the root of the closing triad).