There is a way in which to identify each crofter individually, but it is quite labour intensive because each tenant does not have an identity number as such.We do not know about dates of birth for about two thirds of them because we do not normally ask for dates of birth, although we do when, for example, there are two Iain MacDonalds, one of whom is the father and the other the son, and we would use their dates of birth to distinguish between them.