Ave virgo mater dei, an English three-voice composition from around 1300, combines two structural devices typical of English music of this time: voice-exchange and hocket. Like many of its companion pieces in the so-called Worcester Fragments, only a portion of the original script (shown in Fig. 1) has survived. Recovery of this composition is aided by a number of immediate clues as to how the music (including what has been lost) must originally have been set out in the manuscript.