Metadata play a fundamental role in both DLs and SDIs. Commonly defined
as "structured data about data" or "data which describe attributes of a
resource" or, more simply, "information about data", it is an essential
requirement for locating and evaluating available data. Therefore, this
book focuses on the study of different metadata aspects, which
contribute to a more efficient use of DLs and SDIs. The three main
issues addressed are: the management of nested collections of resources,
the interoperability between metadata schemas, and the integration of
information retrieval techniques to the discovery services of geographic
data catalogs (contributing in this way to avoid metadata content
heterogeneity).