Some other states were also divided into land divisions and land districts; in the nineteenth century, land districts sometimes served as the region name for parts of the state where counties had not been proclaimed yet. Below these are groups of land parcels known as deposited plans, registered plans or title plans (depending on the state). Queensland has registered plans; New South Wales and Western Australia have deposited plans; while Victoria has certified plans. Land can be identified using the number of this plan of subdivision held with the lands department, rather than with a named unit such as a parish (or both can be used); it is becoming increasingly common to use only the plan number. Within these are individual land parcels such as lots; in total there are estimated to be about 10.2 million of these in Australia. The various cadastral units appear on certificates of title, which are given volume and folio numbers; these numbers by themselves are sometimes used to identify land parcels, or in combination with the other units. Detailed maps of these divisions have been required since the introduction of the Torrens title system of a central register of land holdings in South Australia in 1858, which spread to the other colonies. While cadastral data since the 1980s has been digitalised, there remain many old maps showing these divisions held in collections of Australian libraries such as the National Library of Australia, as well as in state libraries.