The Nairs identify themselves as being in many subgroups and there has been debate regarding whether these groups should be considered as subcastes or a mixture both of those and of subdivisions. There have been several attempts to identify these various groups; most of these were prior to the end of British governance in India but Kathleen Gough also studied the issue in 1961. These analyses bear similarities to the "Jatinirnayam", a Malayam work that enumerated 18 main subgroups according to occupation, including drummers, traders, coppersmiths, palanquin bearers, servants, potters and barbers, as well as ranks such as the "Kiriyam" and "Illam". Although the "Jatinirnayam" did not itself distinguish any particular subgroups as ranking higher, subsequent attempts at classification did do so, claiming the various occupations to be traditional ones and stating that only the higher ranked groups were soldiers. Anthropologists, ethnologists and other authors believe that the last name of a Nair was a title which denoted the subgroup ("vibhagam") to which that person belonged and indicated the occupation the person pursued or was bestowed on them by a chief or king. These names included "Nair" itself, "Kurup", "Menon", and "Pillai".