The base-uri accessor returns a sequence containing zero or one uri references.

Document, element, and processing-instruction nodes have a base-uri property. If that property is non-empty, its value is returned.

If the accessor is called on a node that does not have a base-uri property, or whose base-uri property is empty, the base-uri of that node's parent is returned. If the node has no parent, an error is raised. See

The node-kind accessor returns a string value identifying the kind of node on which the accessor was called. One of the following values is returned:

The node-name accessor returns a sequence of zero or one xs:QNames.

The parent accessor returns a sequence containing zero or one nodes.

For nodes that have a parent, parent returns the parent node. For all other nodes, it returns the empty sequence.

If the return value is not the empty sequence, it will always be either an element node or a document node.

The string-value accessor returns a string representation of the node.

For some kinds of nodes, this is part of the node; for other kinds of nodes, it is computed from the string-value of its descendant nodes.

The string-value accessor can be used to recover the lexical representation of an atomic value. The details of converting an atomic value to its string representation are described in the Casting Functions section of . In particular if the atomic value's type is primitive, string-value returns the atomic value's canonical lexical representation for that primitive type as specified in . If the atomic value's type is derived, the lexical representation depends on whether a value is supplied for the type's pattern facet: If no such value is supplied string-value returns the atomic value's canonical lexical representation for the primitive base type. Otherwise string-value returns a lexical representation that matches the value specified for the pattern facet. (This case includes xs:integers.) See .

The typed-value accessor returns the typed-value of the node, which is a sequence of zero or more atomic values. The typed-value is closely related to the node's string-value and its type. For instance when the node's string-value is "3.14" and its type is xs:decimal, the typed-value is a sequence containing the atomic value 3.14 of type decimal. In fact, when the type is an atomic type, typed-value is always the atomic-value constructed from the string-value and the type.

In the general case, typed-value constructs a sequence of atomic values. These values are derived from the string-value of the element and its type, in such a way as to be consistent with validation.

See .

If the node (or node kind) has no typed value, the empty sequence is returned.

The type accessor returns a sequence containing zero or one xs:QName.

For element nodes, type returns the globally declared QName of the type of the node or xs:anyType if it is locally declared or no type information exists.

For attribute nodes, type returns the globally declared QName of the type of the node or xs:anySimpleType if it is locally declared or no type information exists.

For other node kinds, it always returns the empty sequence.

The children accessor returns a sequence containing zero or more nodes.

For document and element nodes, it returns the nodes that are the children of that node. It returns the empty sequence for document and element nodes that have no children.

For all other nodes, it always returns the empty sequence.

A document node or an element node is the parent of each of its child nodes. Nodes never share children: if two nodes have distinct identities, then no child of one node will be a child of the other node.

The attributes accessor returns a sequence containing zero or more attribute nodes.

For element nodes, these are the attributes of the node. For all other nodes, it always returns the empty sequence.

The namespaces accessor returns a sequence containing zero or more namespace nodes.

For element nodes, these are the namespaces of the node. For all other nodes, it always returns the empty sequence.

Document nodes encapsulate XML documents. Documents have the following properties:

Document nodes must satisfy the following constraints.

In a well-formed document, the children of the document node consist exclusively of element nodes, processing-instruction nodes, and comment nodes, and exactly one of these children is an element node. A document node in the data model is more permissive: it allows more than one element node as a child and also permits text nodes as children. See .

A document node can be constructed using document-node which returns a new node with unique identity, distinct from all other nodes.

The constructor takes an optional base URI value and a non-empty sequence of children nodes as arguments.

The sequence of nodes passed as $children must not be empty and must consist only of element, processing instruction, comment, and text nodes. See .

If consecutive text nodes are specified as the children of a document node they are collapsed into one text node whose string value is the concatenation of the string values of the consecutive text nodes.

Two additional accessors are defined on document nodes:

The unparsed-entity-system-id accessor returns the system identifier of an unparsed external entity declared in the specified document. If no entity with the name specified in $entityname exists, or if the entity is not an external unparsed entity, the empty sequence is returned.

The unparsed-entity-public-id accessor returns the public identifier of an unparsed external entity declared in the specified document. If no entity with the name specified in $entityname exists, or if the entity is not an external unparsed entity, or if the entity has no public identifier, the empty sequence is returned.

When a data model fragment is created from the PSVI, a document information item is mapped to a Document Node. The precise transformation is described by specifying the PSVI property corresponding to each argument of the document node constructor:

To construct the value of the $children argument, for each element, processing instruction, comment, and maximal sequence of adjacent characater information items found in the children property, a corresponding Element, Processing Instruction, Comment, and Text node is constructed and that sequence of nodes is used as the value. If present among the children, the document type declaration information item is ignored.

The mapping of the data model to the XML Information Set maps a Document Node to a document information item. The properties of the document information item are constructed as follows:

Element nodes encapsulate XML elements. Elements have the following properties:

Element nodes must satisfy the following constraints.

The element node constructor assures that the first three constraints are satisfied.

An element node can be constructed using element-node which returns a new node with unique identity, distinct from all other nodes.

The constructor takes an expanded-QName, a sequence of namespace nodes, a sequence of attribute nodes, a sequence of child nodes, the node's type, and an optional base URI as arguments.

The sequence of nodes passed as $children must consist only of element, processing instruction, comment, and text nodes.

If consecutive text nodes are specified as the children of an element node they are collapsed into one text node whose string value is the concatenation of the string values of the consecutive text nodes.

To guarantee that the parent-child relationship is invertible, (i.e. that the parent of any child of a node is itself and that any node that has a parent is among its parent's children), the element constructors logically create a copy of all of their namespace, attribute, and children arguments and set the parent property of these nodes to the newly created element node. As long as the parent-child constraint is satisfied, an implementation of the data model may choose to use specialized techniques to avoid creating physical copies of the arguments to an element constructor. See .

The data model permits element nodes without parents. In fact element nodes created by the element node constructor never have parents unless they are enclosed in other node constructors. Such nodes may represent partial results during expression processing.

The base-uri accessor returns the base-uri property of the element node, if it exists. If it does not exist, the base URI of the element's parent is returned. In other words, the value returned must be the same as the value of base-uri(parent()) although implemetations are not required to implement it in that way.

The accessors namespaces and attributes return the same set of namespace and attribute nodes (respectively) that were supplied to the constructor, but they are not constrained to return them in the same order. See

The parent accessor returns the empty sequence if the element has no parent.

If the element node's type is xs:anyType, the typed-value accessor returns the node's string value as xs:anySimpleType. If the type is a complex type with complex content, invoking typed-value raises an error.

The typed-value accessor returns the typed-value of the node, which is a sequence of zero or more atomic values. The typed-value is closely related to the node's string-value and its type. For instance when the node's string-value is "3.14" and its type is xs:decimal, the typed-value is a sequence containing the atomic value 3.14 of type decimal. In fact, when the type is an atomic type, typed-value is always the atomic-value constructed from the string-value and the type.

In the general case, typed-value constructs a sequence of atomic values. These values are derived from the string-value of the element and its type, in such a way as to be consistent with validation.

When a data model fragment is created from the PSVI, an element information item is mapped to an Element Node. The precise transformation is described by specifying the PSVI property corresponding to each argument of the element node constructor.

The unique ID of the element node is an identifier optionally assigned by the user. It corresponds to the normalized value property of the attribute information item in the attributes property that has a type ID, if one exists.

The mapping of the data model to the XML Information Set maps an Element Node to an element information item. The properties of the element information item are constructed as follows:

An implementation must construct the value of the prefix property as if the following algorithm was applied: if the element has at least one namespace node whose namespace URI is the same as the namespace name of the QName returned by the node-name accessor, it returns the local part of the name of that namespace node or the empty string if the namespace node has no name. If there are several such namespace nodes, it chooses one of them arbitrarily. If there is no such namespace node, it generates an arbitrary prefix that is distinct from the node-name of any of the element's namespaces.

If a new prefix is generated, a corresponding namespace information item must be added to the in-scope namespaces property of the element information item. The namespace information item must associate the generated prefix with the namespace name of the QName returned by the element's node-name accessor.

Attribute nodes encapsulate XML attributes. Attributes have the following properties:

The above information associated with an attribute node is set during construction and can be accessed later via the accessor functions.

For convenience, the element node that owns this attribute is called its "parent" even though an attribute node is not a "child" of its parent element.

An attribute node can be constructed using attribute-node which returns a new node with unique identity, distinct from all other nodes.

The constructor takes the attribute's expanded-QName, string value, and type.

Like all other node constructors, the attribute node constructor has the effect of creating a new node with a unique identity, distinct from all other nodes.

When a data model fragment is created from the PSVI an attribute information item is mapped to an Attribute Node. The precise transformation is described by specifying the PSVI property corresponding to each argument of the attribute node constructor.

The mapping of the data model to the XML Information Set maps an Attribute Node to an attribute information item. The properties of the corresponding attribute information item are constructed as follows:

If the attribute node has a parent, an implementation must construct the value of the prefix property in the following way: if the attribute has a parent, in the same way that a prefix would be constructed for that element, otherwise a prefix is chosen arbitrarily, and no attempt is made to associate the prefix with the namespace URI.

Namespace nodes encapsulate XML namespaces. Namespaces have the following properties:

In XPath 1.0, namespace nodes were directly accessible by applications, by means of the namespace axis. In XPath 2.0 the namespace axis is deprecated, and it is not available at all in XQuery 1.0. XPath 2.0 implementations are not required to expose the namespace axis, though they may do so if they wish to offer backwards compatibility. The information held in namespace nodes is instead made available to applications using two functions defined in [Functions and Operators], namely xf:get-in-scope-namespaces and xf:get-namespace-uri-for-prefix. Certain properties of namespace nodes are not exposed by these functions: in particular, properties related to the identity of namespace nodes, their parentage, and their position in document order. Implementations that do not expose the namespace axis can therefore avoid the overhead of maintaining this information.

The above information associated with a namespace node is set during construction and can be accessed later via the accessor functions.

Each element node has an associated set of namespace nodes corresponding to its in-scope namespaces, and that element node acts as the parent of those namespace nodes.

A namespace node can be constructed using namespace-node which returns a new node with unique identity, distinct from all other nodes.

The constructor takes a namespace prefix and the URI of the namespace being declared.

The namespace prefix may be the empty sequence. If the URI is the zero-length string, the prefix must be the empty sequence.

When a data model fragment is created from the PSVI a namespace information item is mapped to a Namespace Node. The precise transformation is described by specifying the PSVI property corresponding to each argument of the attribute node constructor.

The mapping of the data model to the XML Information Set maps a Namespace Node to a namespace information item. The properties of the namespace information item are constructed as follows:

Processing instruction nodes encapsulate XML processing instructions. Processing instructions have the following properties:

A processing instructoin node can be constructed using processing-instruction-node which returns a new node with unique identity, distinct from all other nodes.

The constructor takes an NCName, a string, and an optional base URI.

The string '?>' may not occur within a processing instruction's target or content value ().

When a data model fragment is created from the PSVI, a processing instruction information item is mapped to a Processing Instruction Node. The precise transformation is described by specifying the PSVI property corresponding to each argument of the processing instruction node constructor.

There are no processing instruction nodes for processing instructions that are children of a document type declaration information item.

The mapping of the data model to the XML Information Set maps a Processing Instruction Node to a processing instruction information item. The properties of the processing instruction information item are constructed as follows: