The two halves of the choir (in an architectural sense) in an English cathedral or a large church or chapel: decani is the south side, cantoris the north. The names mean ‘dean’s [side]’, ‘cantor’s [side]’, and refer to the two highest officials of the chapter of a medieval cathedral. The Cantor, or precentor, ranked immediately after the dean in secular cathedral establishments. The dean’s stall was at the west end of the choir, facing east, just to the south of the central aisle; the cantor’s was opposite, north of the aisle. For certain duties the choir (in a musical sense) was also divided into two equal halves. The singers on the dean’s side – decani – took the leading part one week, those on the cantor’s side – cantoris – the next; during the seasons of the three great festivals the alternation was daily. Psalms, canticles and hymns were sung in alternation between the two halves. Together with much other Latin terminology, the names survived the Reformation, and have been used ever since in cathedral music to signify the two halves of the choir....
From the 16th century to the 19th, the choirboys who sang polyphony in the cathedrals of Seville, Toledo, Avila, Segovia, Mexico City, Lima and elsewhere in the Spanish-speaking world were called seises – six being their traditional number at Seville and Toledo cathedrals. The earliest papal bulls designating the income from a prebend for a master of the choirboys in Seville Cathedral were Eugene IV’s Ad exequendum (24 September 1439) and Nicolas V’s Votis illis (27 June 1454). Throughout the next three centuries Seville Cathedral (which set the pattern for the Spanish Indies) had both a master of the altar boys who sang only plainchant, and a master of the seises, generally the maestro de capilla or his deputy. The master of the seises boarded and taught them. When their voices changed, and upon receiving a certificate of good behaviour, they were entitled to a few years’ free tuition and other benefits in the Colegio de S Miguel or in the Colegio de S Isidoro maintained by the Sevillian Chapter. Similar ...