The picture is complicated by the appearance of 'r' in place of 'l' in the names of some 17th-century sources. In Sir William Petty's great survey (the Down Survey), carried out for the Cromwellian regime in the 1650s, the name appears as "Curduf", and in Petty's atlas, Hiberniae Delineatio, (1685), it is spelled "Curduffe".