This title refers to someone set up as Bishop of Rome in opposition to the one already holding the See; 2 lived in Avignon
Most notably in 1353 the Bishop of Porto, Guy de Boulogne, tried to set 
up a... [DOC] [TLE] History of the papacy - Wikipedia [PAR] The history of the papacy, the office held by the pope as head of the Roman 
Catholic Church, according to Catholic doctrine, spans from the time of Peter to 
the present day.