/*
* GeoTools - The Open Source Java GIS Toolkit
* http://geotools.org
*
* (C) 2011, Open Source Geospatial Foundation (OSGeo)
* (C) 2004-2005, Open Geospatial Consortium Inc.
*
* All Rights Reserved. http://www.opengis.org/legal/
*/
/**
* Root package for {@linkplain org.opengis.metadata.MetaData metadata}. The following is adapted from
* <A HREF="http://www.opengis.org/docs/01-111.pdf">OpenGIS® Metadata (Topic 11)</A> specification.
*
* <P ALIGN="justify">The notion of cataloguing a set of related documents together in a discoverable
* series is common in map catalogues. With digital spatial data, the definition of what constitutes a
* "dataset" is more problematic and reflects the institutional and software environments of the originating
* organization. Common metadata can be derived for a series of related spatial datasets, and such metadata
* is generally relevant or can be inherited by each of the dataset instances. Software to support this
* inheritance of metadata for geographic data within a cataloguing system can simplify data entry, update
* and reporting.</P>
*
* <P ALIGN="justify">There is a potential hierarchy of re-usable metadata that can be employed in implementing
* a metadata collection. By creating several levels of abstraction, a linked hierarchy can assist in filtering
* or targeting user queries to the requested level of detail. The hierarchy should not necessarily be interpreted
* to require multiple copies of metadata being managed on-line. Conversely, the definition of general metadata can
* be supplemented by spatially specific metadata that, when queried, either inherits or overrides the general case.
* Through use of pointers this method can reduce the redundancy of metadata managed at a site and provide for different
* views of the holdings by users.</P>
*
* <H2>Data series metadata</H2>
* <P ALIGN="justify">A series or collection of spatial data which share similar characteristics of theme, source date,
* resolution, and methodology. The exact definition of what constitutes a series entry will be determined by the data
* provider. Examples of data series metadata entries may include:</P>
* <UL>
* <LI><P ALIGN="justify">A flight line of digital aerial photographs collected during a single flight with one
* camera and film type. A continuous scan swathe collected from a satellite using the same sensors on a single
* orbital pass.</P></LI>
* <LI><P ALIGN="justify">A collection of raster map data captured from a common series of paper maps.</P></LI>
* <LI><P ALIGN="justify">A collection of vector datasets depicting surface hydrography with associated attribution
* for multiple administrative areas within a country.</P></LI>
* </UL>
* <P ALIGN="justify">The creation of a "data series" metadata level is an optional feature that allows users to
* consult higher-level characteristics for data search. The definition of this type of metadata may be adequate
* for the initial characterization of available spatial data, but may not be adequate for detailed assessment of
* data quality of specific datasets.</P>
*
* <H2>Dataset metadata</H2>
* <P ALIGN="justify">For the purposes of this specification, a dataset should be a consistent spatial data product
* instance that can be generated or made available by a spatial data distributor. A dataset may be a member of a
* data series, as defined in the previous subclause. A dataset may be composed of a set of identified feature types
* and instances, and attribute types and instances as described in the following four subclauses.</P>
*
* <P ALIGN="justify">On a demand basis, metadata from series and dataset information will be merged to present the
* user with a view of the metadata at the dataset level of abstraction. Metadata for which no hierarchy is listed
* are interpreted to be "dataset" metadata, by default.</P>
*
* <H2>Feature type metadata</H2>
* <P ALIGN="justify">Spatial constructs known as features are grouped spatial primitives (0-, 1- and 2-dimensional
* geometric objects) that have a common identity. Spatial data services may elect to support feature type-level
* metadata where it is available and make such metadata available for query or retrieval. Feature Type -level metadata,
* together with feature instance-, attribute type- and attribute instance-level metadata, will be grouped into datasets,
* as defined in the previous subclause. Examples of feature type metadata entries may include:</P>
* <UL>
* <LI>All bridges within a dataset.</LI>
* </UL>
*
* <H2>Feature instance metadata</H2>
* <P ALIGN="justify">Feature instances are spatial constructs (features) that have a direct correspondence with a
* real world object. Spatial data services may elect to support feature instance-level metadata where it is available
* and make such metadata available for query or retrieval. Feature Instance-level metadata, together with feature type-,
* attribute type- and attribute instance-level metadata, will be grouped into datasets. Examples of feature
* instance metadata entries may include:</P>
* <UL>
* <LI>The Sydney harbour bridge.</LI>
* <LI>The Golden Gate bridge, in San Francisco.</LI>
* </UL>
*
* <H2>Attribute type metadata</H2>
* <P ALIGN="justify">Attribute types are the digital parameters that describe a common aspect of grouped spatial primitives
* (0-, 1- and 2- dimensional geometric objects). Spatial data services may elect to support attribute type-level metadata
* where it is available and make such metadata available for query or retrieval. Attribute type-level metadata, together with
* feature type-, feature instance and attribute instance-level metadata, will be grouped into datasets. Examples of attribute
* type metadata entries may include:</P>
* <UL>
* <LI>Overhead clearance associated with a bridge.</LI>
* </UL>
*
* <H2>Attribute instance metadata</H2>
* <P ALIGN="justify">Attribute instances are the digital parameters that describe an aspect of a feature instance.
* Spatial data services may elect to support attribute instance-level metadata where it is available and make such
* metadata available for query or retrieval. Attribute instance-level metadata, together with feature type-, feature
* instance and attribute typelevel metadata, will be grouped into datasets. Examples of attribute instance metadata
* entries may include:</P>
* <UL>
* <LI>The overhead clearance associated with a specific bridge across a road.</LI>
* </UL>
*
* @version <A HREF="http://www.opengeospatial.org/standards/as#01-111">ISO 19115</A>
* @since GeoAPI 2.0
*/
package org.opengis.metadata;