Cambrai was divided in two equal parts and each half installed in either the right or left side of the choir of the church. An entry in the capitulary acts of February 4, 1473, shows that on only three days of the year did the singers come together to perform in the middle of the aisle: Maundy Thursday, Holy Saturday, and Pentecost…On all other days, they sang from either side, each half grouped around its own lectern, and performing from its own music book. A bizarre confirmation of the existing space between the two sides comes from an entry of September 9, 1493, that reprimands the lesser vicars for throwing meat and bones from one side of the choir to the other during the divine service
Emphasis mine. Via Unquiet Thoughts (whose music as the duet Mignarda I highly recommend).