um ▁with ▁disc ant ▁cla us ula e ▁or ▁simply ▁replacing ▁existing ▁cla us ula e ▁with ▁shorter ▁ones . ▁Some ▁ 1 5 4 ▁cla us ula e ▁have ▁been ▁attributed ▁to ▁P é rot in ▁but ▁many ▁other ▁cla us ula e ▁are ▁elaborate ▁compos itions ▁that ▁would ▁actually ▁expand ▁the ▁compos itions ▁in ▁the ▁Liber , ▁and ▁these ▁sty list ically ▁res emble ▁his ▁known ▁works ▁which ▁are ▁on ▁a ▁much ▁gr ander ▁scale ▁than ▁those ▁of ▁his ▁prede cess or , ▁and ▁hence ▁do ▁not ▁represent ▁" ab bre viation ". ▁An ▁alternative ▁rendering ▁of ▁abbre via v it ▁is ▁to ▁write ▁down , ▁suggesting ▁that ▁he ▁actually ▁prepared ▁a ▁new ▁edition ▁using ▁his ▁better ▁developed ▁system ▁of ▁rh yth mic ▁notation , ▁including ▁mens ural ▁notation , ▁as ▁mentioned ▁by ▁An onymous ▁IV . ▁▁ ▁Two ▁styles ▁emer ged ▁from ▁the ▁organ um ▁du pl um , ▁the ▁" fl or id " ▁and ▁" dis c ant " ▁( dis c ant us ). ▁The ▁former ▁was ▁more ▁typical ▁of ▁Lé on in , ▁the ▁latter ▁of ▁P é rot in , ▁though ▁this ▁indirect ▁att ribution ▁has ▁been ▁challeng ed . ▁An onymous ▁IV ▁described ▁Lé on in ▁as ▁optim us ▁organ ista ▁( the ▁best ▁composer ▁of ▁org ana ) ▁but ▁P é rot in , ▁who ▁re vised ▁the ▁former ' s ▁Magn us ▁Liber ▁Or g ani ▁( Gre at ▁Organ um ▁Book ), ▁as ▁optim us ▁disc ant or ▁referring ▁to ▁his