GML base schema for GML 3
Components to support the GML encoding model.
The abstract Schematron rules can be used by any schema that includes gmlBase.
GML is an OGC Standard.
Copyright (c) 2001,2005,2010 Open Geospatial Consortium.
To obtain additional rights of use, visit http://www.opengeospatial.org/legal/ .
Properties
attribute form default:
unqualified
element form default:
qualified
version:
3.1.1.2
Element gml:metaDataProperty
Namespace
http://www.opengis.net/gml
Annotations
Contains or refers to a metadata package that contains metadata properties.
Reference to an XML Schema fragment that specifies the content model of the propertys value. This is in conformance with the
XML Schema Section 4.14 Referencing Schemas from Elsewhere.
<element name="metaDataProperty" type="gml:MetaDataPropertyType"><annotation><documentation>Contains or refers to a metadata package that contains metadata properties.</documentation></annotation></element>
Element gml:description
Namespace
http://www.opengis.net/gml
Annotations
Contains a simple text description of the object, or refers to an external description.
Reference to an XML Schema fragment that specifies the content model of the propertys value. This is in conformance with the
XML Schema Section 4.14 Referencing Schemas from Elsewhere.
<element name="description" type="gml:StringOrRefType"><annotation><documentation>Contains a simple text description of the object, or refers to an external description.</documentation></annotation></element>
Element gml:name
Namespace
http://www.opengis.net/gml
Annotations
Label for the object, normally a descriptive name. An object may have several names, typically assigned by different authorities.
The authority for a name is indicated by the value of its (optional) codeSpace attribute. The name may or may not be unique,
as determined by the rules of the organization responsible for the codeSpace.
<element name="name" type="gml:CodeType"><annotation><documentation>Label for the object, normally a descriptive name. An object may have several names, typically assigned by different authorities. The authority for a name is indicated by the value of its (optional) codeSpace attribute. The name may or may not be unique, as determined by the rules of the organization responsible for the codeSpace.</documentation></annotation></element>
Element gml:_Object
Namespace
http://www.opengis.net/gml
Annotations
This abstract element is the head of a substitutionGroup hierararchy which may contain either simpleContent or complexContent
elements. It is used to assert the model position of "class" elements declared in other GML schemas.
<element name="_Object" abstract="true"><annotation><documentation>This abstract element is the head of a substitutionGroup hierararchy which may contain either simpleContent or complexContent elements. It is used to assert the model position of "class" elements declared in other GML schemas.</documentation></annotation></element>
Element gml:_GML
Namespace
http://www.opengis.net/gml
Annotations
Global element which acts as the head of a substitution group that may include any element which is a GML feature, object,
geometry or complex value
Database handle for the object. It is of XML type ID, so is constrained to be unique in the XML document within which it
occurs. An external identifier for the object in the form of a URI may be constructed using standard XML and XPointer methods.
This is done by concatenating the URI for the document, a fragment separator, and the value of the id attribute.
Source
<element name="_GML" type="gml:AbstractGMLType" abstract="true" substitutionGroup="gml:_Object"><annotation><documentation>Global element which acts as the head of a substitution group that may include any element which is a GML feature, object, geometry or complex value</documentation></annotation></element>
Element gml:Bag
Namespace
http://www.opengis.net/gml
Annotations
Generic GML element to contain a heterogeneous collection of GML _Objects
Database handle for the object. It is of XML type ID, so is constrained to be unique in the XML document within which it
occurs. An external identifier for the object in the form of a URI may be constructed using standard XML and XPointer methods.
This is done by concatenating the URI for the document, a fragment separator, and the value of the id attribute.
Source
<element name="Bag" type="gml:BagType" substitutionGroup="gml:_GML"><annotation><documentation>Generic GML element to contain a heterogeneous collection of GML _Objects</documentation></annotation></element>
Reference to an XML Schema fragment that specifies the content model of the propertys value. This is in conformance with the
XML Schema Section 4.14 Referencing Schemas from Elsewhere.
Database handle for the object. It is of XML type ID, so is constrained to be unique in the XML document within which it
occurs. An external identifier for the object in the form of a URI may be constructed using standard XML and XPointer methods.
This is done by concatenating the URI for the document, a fragment separator, and the value of the id attribute.
Source
<element name="Array" type="gml:ArrayType" substitutionGroup="gml:_GML"><annotation><documentation>Generic GML element to contain a homogeneous array of GML _Objects</documentation></annotation></element>
Element gml:_MetaData
Namespace
http://www.opengis.net/gml
Annotations
Abstract element which acts as the head of a substitution group for packages of MetaData properties.
Database handle for the object. It is of XML type ID, so is constrained to be unique in the XML document within which it
occurs. An external identifier for the object in the form of a URI may be constructed using standard XML and XPointer methods.
This is done by concatenating the URI for the document, a fragment separator, and the value of the id attribute.
Source
<element name="_MetaData" type="gml:AbstractMetaDataType" abstract="true" substitutionGroup="gml:_Object"><annotation><documentation>Abstract element which acts as the head of a substitution group for packages of MetaData properties.</documentation></annotation></element>
Element gml:GenericMetaData
Namespace
http://www.opengis.net/gml
Annotations
Concrete element in the _MetaData substitution group, which permits any well-formed XML content. Intended to act as a container
for metadata defined in external schemas, for which it is not possible to add the concrete components to the GML _MetaData
substitution group directly. Deprecated with GML version 3.1.0.
Database handle for the object. It is of XML type ID, so is constrained to be unique in the XML document within which it
occurs. An external identifier for the object in the form of a URI may be constructed using standard XML and XPointer methods.
This is done by concatenating the URI for the document, a fragment separator, and the value of the id attribute.
Source
<element name="GenericMetaData" type="gml:GenericMetaDataType" substitutionGroup="gml:_MetaData"><annotation><documentation>Concrete element in the _MetaData substitution group, which permits any well-formed XML content. Intended to act as a container for metadata defined in external schemas, for which it is not possible to add the concrete components to the GML _MetaData substitution group directly. Deprecated with GML version 3.1.0.</documentation></annotation></element>
Reference to an XML Schema fragment that specifies the content model of the propertys value. This is in conformance with the
XML Schema Section 4.14 Referencing Schemas from Elsewhere.
Reference to an XML Schema fragment that specifies the content model of the propertys value. This is in conformance with the
XML Schema Section 4.14 Referencing Schemas from Elsewhere.
<element name="_strictAssociation" type="gml:AssociationType" abstract="true"><annotation><appinfo><sch:pattern name="refAndContent co-occurence prohibited"><sch:rule context="gml:_strictAssociation"><sch:extends rule="hrefOrContent"/></sch:rule></sch:pattern></appinfo><documentation>must carry a reference to an object or contain an object but not both</documentation></annotation></element>
Reference to an XML Schema fragment that specifies the content model of the propertys value. This is in conformance with the
XML Schema Section 4.14 Referencing Schemas from Elsewhere.
All complexContent GML elements are directly or indirectly derived from this abstract supertype
to establish a hierarchy of GML types that may be distinguished from other XML types by their ancestry.
Elements in this hierarchy may have an ID and are thus referenceable.
Database handle for the object. It is of XML type ID, so is constrained to be unique in the XML document within which it
occurs. An external identifier for the object in the form of a URI may be constructed using standard XML and XPointer methods.
This is done by concatenating the URI for the document, a fragment separator, and the value of the id attribute.
Source
<complexType name="AbstractGMLType" abstract="true"><annotation><documentation>All complexContent GML elements are directly or indirectly derived from this abstract supertype
to establish a hierarchy of GML types that may be distinguished from other XML types by their ancestry.
Elements in this hierarchy may have an ID and are thus referenceable.</documentation></annotation><sequence><group ref="gml:StandardObjectProperties"/></sequence><attribute ref="gml:id" use="optional"/></complexType>
Reference to an XML Schema fragment that specifies the content model of the propertys value. This is in conformance with the
XML Schema Section 4.14 Referencing Schemas from Elsewhere.
<complexType name="MetaDataPropertyType"><annotation><documentation>Base type for complex metadata property types.</documentation></annotation><sequence minOccurs="0"><any processContents="lax"/><!-- <element ref="gml:_MetaData"/> --></sequence><attributeGroup ref="gml:AssociationAttributeGroup"/><attribute name="about" type="anyURI" use="optional"/></complexType>
Complex Type gml:StringOrRefType
Namespace
http://www.opengis.net/gml
Annotations
This type is available wherever there is a need for a "text" type property. It is of string type, so the text can be included
inline, but the value can also be referenced remotely via xlinks from the AssociationAttributeGroup. If the remote reference
is present, then the value obtained by traversing the link should be used, and the string content of the element can be used
for an annotation.
Reference to an XML Schema fragment that specifies the content model of the propertys value. This is in conformance with the
XML Schema Section 4.14 Referencing Schemas from Elsewhere.
<complexType name="StringOrRefType"><annotation><documentation>This type is available wherever there is a need for a "text" type property. It is of string type, so the text can be included inline, but the value can also be referenced remotely via xlinks from the AssociationAttributeGroup. If the remote reference is present, then the value obtained by traversing the link should be used, and the string content of the element can be used for an annotation.</documentation></annotation><simpleContent><extension base="string"><attributeGroup ref="gml:AssociationAttributeGroup"/></extension></simpleContent></complexType>
Complex Type gml:ReferenceType
Namespace
http://www.opengis.net/gml
Annotations
A pattern or base for derived types used to specify complex types corresponding to a UML aggregation association. An instance
of this type serves as a pointer to a remote Object.
Reference to an XML Schema fragment that specifies the content model of the propertys value. This is in conformance with the
XML Schema Section 4.14 Referencing Schemas from Elsewhere.
<complexType name="ReferenceType"><annotation><documentation>A pattern or base for derived types used to specify complex types corresponding to a UML aggregation association. An instance of this type serves as a pointer to a remote Object.</documentation></annotation><sequence/><attributeGroup ref="gml:AssociationAttributeGroup"/></complexType>
Complex Type gml:BagType
Namespace
http://www.opengis.net/gml
Annotations
A non-abstract generic collection type that can be used as a document element for a collection of any GML types - Geometries,
Topologies, Features ...
FeatureCollections may only contain Features. GeometryCollections may only contain Geometrys. Bags are less constrained
they must contain objects that are substitutable for gml:_Object. This may mix several levels, including Features, Definitions,
Dictionaries, Geometries etc.
The content model would ideally be
member 0..*
members 0..1
member 0..*
for maximum flexibility in building a collection from both homogeneous and distinct components:
included "member" elements each contain a single Object
an included "members" element contains a set of Objects
However, this is non-deterministic, thus prohibited by XSD.
Database handle for the object. It is of XML type ID, so is constrained to be unique in the XML document within which it
occurs. An external identifier for the object in the form of a URI may be constructed using standard XML and XPointer methods.
This is done by concatenating the URI for the document, a fragment separator, and the value of the id attribute.
Source
<complexType name="BagType"><annotation><documentation>A non-abstract generic collection type that can be used as a document element for a collection of any GML types - Geometries, Topologies, Features ...
FeatureCollections may only contain Features. GeometryCollections may only contain Geometrys. Bags are less constrained they must contain objects that are substitutable for gml:_Object. This may mix several levels, including Features, Definitions, Dictionaries, Geometries etc.
The content model would ideally be
member 0..*
members 0..1
member 0..*
for maximum flexibility in building a collection from both homogeneous and distinct components:
included "member" elements each contain a single Object
an included "members" element contains a set of Objects
However, this is non-deterministic, thus prohibited by XSD.</documentation></annotation><complexContent><extension base="gml:AbstractGMLType"><sequence><element ref="gml:member" minOccurs="0" maxOccurs="unbounded"/><element ref="gml:members" minOccurs="0"/></sequence></extension></complexContent></complexType>
Complex Type gml:AssociationType
Namespace
http://www.opengis.net/gml
Annotations
A pattern or base for derived types used to specify complex types corresponding to an unspecified UML association - either
composition or aggregation. Restricts the cardinality of Objects contained in the association to a maximum of one. An instance
of this type can contain an element representing an Object, or serve as a pointer to a remote Object.
Descendents of this type can be restricted in an application schema to
* allow only specified classes as valid participants in the aggregation
* allow only association by reference (i.e. empty the content model) or by value (i.e. remove the xlinks).
When used for association by reference, the value of the gml:remoteSchema attribute can be used to locate a schema fragment
that constrains the target instance.
In many cases it is desirable to impose the constraint prohibiting the occurence of both reference and value in the same instance,
as that would be ambiguous. This is accomplished by adding a directive in the annotation element of the element declaration.
This directive can be in the form of normative prose, or can use a Schematron pattern to automatically constrain co-occurrence
- see the declaration for _strictAssociation below.
If co-occurence is not prohibited, then both a link and content may be present. If this occurs in an instance, then the rule
for interpretation is that the instance found by traversing the href provides the normative value of the property, and should
be used when possible. The value(s) included as content may be used if the remote instance cannot be resolved. This may
be considered to be a "cached" version of the value(s).
Reference to an XML Schema fragment that specifies the content model of the propertys value. This is in conformance with the
XML Schema Section 4.14 Referencing Schemas from Elsewhere.
<complexType name="AssociationType"><annotation><documentation>A pattern or base for derived types used to specify complex types corresponding to an unspecified UML association - either composition or aggregation. Restricts the cardinality of Objects contained in the association to a maximum of one. An instance of this type can contain an element representing an Object, or serve as a pointer to a remote Object.
Descendents of this type can be restricted in an application schema to
* allow only specified classes as valid participants in the aggregation
* allow only association by reference (i.e. empty the content model) or by value (i.e. remove the xlinks).
When used for association by reference, the value of the gml:remoteSchema attribute can be used to locate a schema fragment that constrains the target instance.
In many cases it is desirable to impose the constraint prohibiting the occurence of both reference and value in the same instance, as that would be ambiguous. This is accomplished by adding a directive in the annotation element of the element declaration. This directive can be in the form of normative prose, or can use a Schematron pattern to automatically constrain co-occurrence - see the declaration for _strictAssociation below.
If co-occurence is not prohibited, then both a link and content may be present. If this occurs in an instance, then the rule for interpretation is that the instance found by traversing the href provides the normative value of the property, and should be used when possible. The value(s) included as content may be used if the remote instance cannot be resolved. This may be considered to be a "cached" version of the value(s).</documentation></annotation><sequence minOccurs="0"><element ref="gml:_Object"/></sequence><attributeGroup ref="gml:AssociationAttributeGroup"/></complexType>
Complex Type gml:ArrayAssociationType
Namespace
http://www.opengis.net/gml
Annotations
A base for derived types used to specify complex types containing an array of objects, by unspecified UML association - either
composition or aggregation. An instance of this type contains elements representing Objects.
Ideally this type would be derived by extension of AssociationType.
However, this leads to a non-deterministic content model, since both the base and the extension have minOccurs="0", and is
thus prohibited in XML Schema.
<complexType name="ArrayAssociationType"><annotation><documentation>A base for derived types used to specify complex types containing an array of objects, by unspecified UML association - either composition or aggregation. An instance of this type contains elements representing Objects.
Ideally this type would be derived by extension of AssociationType.
However, this leads to a non-deterministic content model, since both the base and the extension have minOccurs="0", and is thus prohibited in XML Schema.</documentation></annotation><sequence><element ref="gml:_Object" minOccurs="0" maxOccurs="unbounded"/></sequence></complexType>
Complex Type gml:ArrayType
Namespace
http://www.opengis.net/gml
Annotations
A non-abstract generic collection type that can be used as a document element for a homogeneous collection of any GML types
- Geometries, Topologies, Features ...
Database handle for the object. It is of XML type ID, so is constrained to be unique in the XML document within which it
occurs. An external identifier for the object in the form of a URI may be constructed using standard XML and XPointer methods.
This is done by concatenating the URI for the document, a fragment separator, and the value of the id attribute.
Source
<complexType name="ArrayType"><annotation><documentation>A non-abstract generic collection type that can be used as a document element for a homogeneous collection of any GML types - Geometries, Topologies, Features ...</documentation></annotation><complexContent><extension base="gml:AbstractGMLType"><sequence><element ref="gml:members" minOccurs="0"/></sequence></extension></complexContent></complexType>
Database handle for the object. It is of XML type ID, so is constrained to be unique in the XML document within which it
occurs. An external identifier for the object in the form of a URI may be constructed using standard XML and XPointer methods.
This is done by concatenating the URI for the document, a fragment separator, and the value of the id attribute.
Source
<complexType name="AbstractMetaDataType" abstract="true" mixed="true"><annotation><documentation>An abstract base type for complex metadata types.</documentation></annotation><attribute ref="gml:id" use="optional"/></complexType>
Database handle for the object. It is of XML type ID, so is constrained to be unique in the XML document within which it
occurs. An external identifier for the object in the form of a URI may be constructed using standard XML and XPointer methods.
This is done by concatenating the URI for the document, a fragment separator, and the value of the id attribute.
Source
<complexType name="GenericMetaDataType" mixed="true"><annotation><documentation>Deprecated with GML version 3.1.0.</documentation></annotation><complexContent mixed="true"><extension base="gml:AbstractMetaDataType"><sequence><any processContents="lax" minOccurs="0" maxOccurs="unbounded"/></sequence></extension></complexContent></complexType>
Attribute @gml:remoteSchema
Namespace
http://www.opengis.net/gml
Annotations
Reference to an XML Schema fragment that specifies the content model of the propertys value. This is in conformance with the
XML Schema Section 4.14 Referencing Schemas from Elsewhere.
<attribute name="remoteSchema" type="anyURI"><annotation><documentation>Reference to an XML Schema fragment that specifies the content model of the propertys value. This is in conformance with the XML Schema Section 4.14 Referencing Schemas from Elsewhere.</documentation></annotation></attribute>
Database handle for the object. It is of XML type ID, so is constrained to be unique in the XML document within which it
occurs. An external identifier for the object in the form of a URI may be constructed using standard XML and XPointer methods.
This is done by concatenating the URI for the document, a fragment separator, and the value of the id attribute.
<attribute name="id" type="ID"><annotation><documentation>Database handle for the object. It is of XML type ID, so is constrained to be unique in the XML document within which it occurs. An external identifier for the object in the form of a URI may be constructed using standard XML and XPointer methods. This is done by concatenating the URI for the document, a fragment separator, and the value of the id attribute.</documentation></annotation></attribute>
Element Group gml:StandardObjectProperties
Namespace
http://www.opengis.net/gml
Annotations
This content model group makes it easier to construct types that
derive from AbstractGMLType and its descendents "by restriction".
A reference to the group saves having to enumerate the standard object properties.
<group name="StandardObjectProperties"><annotation><documentation>This content model group makes it easier to construct types that
derive from AbstractGMLType and its descendents "by restriction".
A reference to the group saves having to enumerate the standard object properties.</documentation></annotation><sequence><element ref="gml:metaDataProperty" minOccurs="0" maxOccurs="unbounded"/><element ref="gml:description" minOccurs="0"/><element ref="gml:name" minOccurs="0" maxOccurs="unbounded"><annotation><documentation>Multiple names may be provided. These will often be distinguished by being assigned by different authorities, as indicated by the value of the codeSpace attribute. In an instance document there will usually only be one name per authority.</documentation></annotation></element></sequence></group>
Attribute Group gml:AssociationAttributeGroup
Namespace
http://www.opengis.net/gml
Annotations
Attribute group used to enable property elements to refer to their value remotely. It contains the simple link components
from xlinks.xsd, with all members optional, and the remoteSchema attribute, which is also optional. These attributes can
be attached to any element, thus allowing it to act as a pointer. The 'remoteSchema' attribute allows an element that carries
link attributes to indicate that the element is declared in a remote schema rather than by the schema that constrains the
current document instance.
Reference to an XML Schema fragment that specifies the content model of the propertys value. This is in conformance with the
XML Schema Section 4.14 Referencing Schemas from Elsewhere.
<attributeGroup name="AssociationAttributeGroup"><annotation><documentation>Attribute group used to enable property elements to refer to their value remotely. It contains the simple link components from xlinks.xsd, with all members optional, and the remoteSchema attribute, which is also optional. These attributes can be attached to any element, thus allowing it to act as a pointer. The 'remoteSchema' attribute allows an element that carries link attributes to indicate that the element is declared in a remote schema rather than by the schema that constrains the current document instance.</documentation></annotation><attributeGroup ref="xlink:simpleAttrs"/><attribute ref="gml:remoteSchema" use="optional"/></attributeGroup>
