OGC 07-147r2
Copyright © 2007, 2008 Open Geospatial Consortium, Inc. All Rights Reserved.
13 Each element subclause includes a XML structure section that shows the content model for
the described element as a representative XML instance, using the following conventions: • The minimum and maximum occurrence of elements and attributes required by its
schema type are shown in square brackets, for example [0..1]. Such occurrence requirements are necessary but insufficient in that additional occurrence requirements
are asserted within this OGC® Standard.
• Elements are listed in the required document order. • Choice model group information is represented by Start Choice ... End Choice.
• Where the type for an element derives by extension from a base type, the elements and
attributes that have been added to the base types content are shown in bold.
6 KML Model Overview
6.1 KML Architecture
This section provides an overview of the KML schema type hierarchy. While element names are used, they represent the schema types that define their content. As KML is an XML
grammar, element names are case-sensitive and must appear exactly as specified in the KML schema document.
In KML, some types are derived from a parent type. A derived type inherits all of the elements of its parent type and may add some specific element content of its own. KML also
includes abstract elements whose type is also abstract. Such abstract types are used to establish schema type hierarchies. Abstract elements may serve as placeholders for elements
that substitute for them in the XML Schema sense.
The core KML type hierarchy is represented in the following nested list. It shows the abstract KML elements that serve as the head of a substitution group for its corresponding
type in brackets. The abstract elements themselves follow an identical substitution hierarchy. For example,
kml:AbstractContainerGroup
substitutes for
kml:AbstractFeatureGroup
, which in turn substitutes for
kml:AbstractObjectGroup
.
• kml:AbstractObjectGroup kml:AbstractObjectType • kml:AbstractFeatureGroup kml:AbstractFeatureType
• AbstractContainerGroup kml:AbstractContainerType • AbstractOverlayGroup kml:AbstractOverlayType
• AbstractGeometryGroup kml:AbstractGeometryType
OGC 07-147r2
14
Copyright © 2007, 2008 Open Geospatial Consortium, Inc. All Rights Reserved. • AbstractStyleSelectorGroup kml:AbstractStyleSelectorType
• AbstractSubStyleGroup kml:AbstractSubStyleType • AbstractColorStyleGroup kml:AbstractColorStyleType
• AbstractLatLonBox kml:AbstractLatLonBoxType • AbstractViewGroup kml: AbstractViewType
• AbstractTimePrimitiveGroup kml:AbstractTimePrimitiveType
These abstract elements and their associated base types define the core of the language. All concrete elements derived from
kml:AbstractObjectGroup
may have an assigned identifier.
Simple elements are generally referred to as KML fields. Such elements are of XML Schema simple types or KML field types defined in the KML schema. KML field types are
specified in clause 16 Field Types.
6.2 Coordinate Reference System
