This data set (LCDB v4.0 Change) allows users to track changes back to earlier versions, and to reconcile derived quantities, such as the total area of a class in a region, to those derived from earlier LCDB versions. Additionally the authority (and date) for mapping the change is recorded in this database where such a change has been manually mapped.
LCDB v4.0 is an update on the previous LCDB v3.3 map. This version has the four timesteps (summer 1996/97, summer 2001/02, summer 2008/09 and summer 2011/12). It corrects errors errors identified in the earlier version. Only the changed polygons (temporal or non-temporal) are retained. This layer was produced with a tolerance of1cm as a zero tolerance can generate slivers too small for the portal software to project correctly.