NVIS is a compilation of several surveys of varying scales, that were re-coded and re-attributed for the National Vegetation Information System (NVIS). This forms Theme 3 of the National Land & Water Audit of Australia, 2000 (NLWRA2000). The goal of the vegetation component (Theme 3) of the Audit is to 'Develop a national information system that provides for easily accessible and nationally consistent data on the extent and condition of Australia's vegetation, thereby improving our ability to make better natural resource management decisions.' Work for NVIS involved some line-work changes as well as creation of an attribute data-base for each original survey data set. For each survey a 'PRE1750' and an 'EXTANT' dataset was produced. The 'PRE1750' or 'pre-clearing' dataset represents, in theory, the vegetation that existed in that particular survey region before the arrival of the white man. In all, the surveys attributed to NVIS standard in the NT, this 'PRE1750' coverage was taken to be the original survey coverage produced. The 'EXTANT' or present day dataset represents, in theory, the present day (eg year 1998) vegetation coverage. This was produced by updating the 'PRE1750' dataset with cleared or modified vegetation. This dataset was recently renamed as NVIS_2007.