Data maintenance is often an expensive yet neglected aspect of
managing GIS data. Each data layer is unique and will have its own
system for making and tracking updates. By consequence, tools for
data maintenance are generally not built into GIS software.
This guideline contains a collection of techniques and procedures for
managing GIS data layer updates. Appropriate techniques can be
adopted (with modification as need be) for a given data layer. Some
data layers change very little over time, and may only require simple
procedures for reporting errors and making rare revisions. Other layers
change often and require procedures for recording updates in a manner
that supports quality control and tracking of changes over time. A full
range of techniques is discussed here, including methods which enable
an audit trail of modifications over time for a given feature. The text is
primarily intended for those familiar with the Arc/Info GIS software.