Q-S

QNAME ( XML NAMESPACES)

A qualified name. It is either a simple name (an NCName ) or a name preceded by a namespace prefix and a colon .

See also LEXICAL QNAME (XPATH).

See also EXPANDED QNAME (XPATH).

RANGE VARIABLE (XPATH)

A variable declared in a «for » , «some » , or «every » expression, which is bound to each item in a sequence in turn : for example, the variable $i in «for $i in 1 to 5 return $i*$i » .

REGULAR EXPRESSION (XPATH)

A regular expression is a pattern that strings may or may not match. Regular expressions can be used in the three functions matches() , replace() , and tokenize() defined in XPath, and in the <xsl:analyze-string> instruction in XSLT.

RESULT TREE (XSLT)

The output of a stylesheet. A stylesheet defines a transformation from a source tree to a result tree. XSLT 2.0 allows multiple result trees to be created. The final stage of processing is normally to serialize the result tree as a stream of characters or bytes: this is controlled by the selected output method.

REVERSE AXIS (XPATH)

An axis containing a sequence of nodes that precede the context node in document order. Within a predicate of an axis step that uses a reverse axis (for example, « preceding -sibling::x[position() = 1 to 3] » ), position numbers count the nodes in reverse document order. However, as with any other axis step, the result of the expression is in forwards document order. So this expression returns the last three «x » nodes before the context node, in document order.

ROOT NODE ( XPATH )

The top-most node in a tree; any node that has no parent. In XPath 2.0, any kind of node may be a root node. A root node that represents a complete XML document is now referred to as a document node.

SCHEMA (SCHEMA)

In this book the term schema, unless otherwise specified, always means a schema defined using the W3C XML Schema language. A schema can be regarded as a collection of element declarations, attribute declarations, and type definitions. A schema document, by contrast, is the XML document rooted at an <xs:schema> element (which one might regard as containing one module of a schema).

SCHEMA COMPONENT (SCHEMA)

A generic term for element declarations, attribute declarations, and type definitions.

SCHEMA TYPE (THIS BOOK)

A type as defined in XML Schema: either a complex type or a simple type. The type may be named, or it may be anonymous. The term includes both built-in types (such as xs:integer) and user -defined types.

SELF AXIS (XPATH)

The self axis contains a single node, the context node. It makes no difference whether it is regarded as a forwards axis or a reverse axis. The principal node kind of the self axis is elements, which means that when the context node is an attribute, an axis step of the form «self::* » or «self::xyz » will not select that attribute.

SEQUENCE (XPATH)

A sequence in the XPath data model is an ordered collection of items. The items may be atomic values or references to nodes in a tree. A sequence containing no items is referred to as the empty sequence. Sequences have no identity of their own; two sequences containing the same items cannot be distinguished.

SEQUENCE CONSTRUCTOR ( XSLT )

A sequence of XSLT instructions, extension instructions, literal result elements, and text nodes, forming the content of an <xsl:template> element or of various other elements in the stylesheet. When the sequence constructor is evaluated, any instructions and extension instructions are evaluated according to the rules for each one, while any literal result elements and text nodes are copied to the result sequence. In most cases the result sequence will be used to form the content of a new node in a result tree, but this depends on the instruction that contains the sequence constructor.

SEQUENCE TYPE (XPATH)

A sequence type is a definition that constrains the permitted values of a sequence. It has two parts : an item type, which constrains the type of the items in the sequence, and a cardinality, which constrains the number of items in the sequence. The cardinality may be zero-or-one, exactly-one , zero-or-more, or one-or-more .

SERIALIZATION (XSLT)

Serialization is the reverse of parsing: it takes a document represented as a tree in the XPath data model, and converts it into a lexical XML document.

SIMPLE TYPE (SCHEMA)

A simple type in XML Schema describes values that can be written as text, with no embedded markup. Simple types divide into atomic types, list types, and union types. Attributes always have a simple type; the content of an element may be either a simple or a complex type. XML Schema defines a number of built-in simple types, but further simple types can be defined in a user-written schema.

SIMPLIFIED STYLESHEET MODULE (XSLT)

A simplified stylesheet module is a stylesheet module consisting solely of a literal result element which is evaluated using the root of the source document as the context node.

SOURCE DOCUMENT (XPATH)

The principal source document is the XML document to which the stylesheet is being applied. Secondary source documents can be loaded using the document() function.

STATIC CONTEXT (XPATH)

The static context of an XPath expression is the total collection of information available to the XPath engine at compile time. This includes the namespace declarations that are in scope, the names and types of declared variables , the base URI of the expression, and the collations that are available.

STATIC ERROR (XPATH)

A static error is an error detected during the analysis phase, that is, at compile time.

STATIC TYPE (XPATH)

Every expression (and subexpression) has a static type. This is a sequence type, representing the best possible inference that can be made about the dynamic type of the value that will be returned when the expression is evaluated. For example, the static type of the expression «@* » might be «attribute()* » . In an XPath processor that implements strict static typing, a type error will be reported if the static type of an expression is not a subtype of the type required by the context in which the expression is used.

STEP (XPATH)

A step is used within a path expression to navigate from one node to a sequence of related nodes. The most common kind of step is an axis step, which is defined by an axis, giving the direction of navigation; a node test, which defines constraints on the type of and names of the target nodes; and zero or more predicates, which define arbitrary constraints that the target nodes must satisfy .

STRING (XPATH)

One of the allowed data types for the value of an XPath expression. It is a sequence of zero or more Unicode characters (the same character set as is used in XML).

STRING VALUE (XPATH)

Every node has a string value. For a text node the string value is the textual content; for an element it is the concatenation of the string values of its descendant text nodes (that is, the textual content of the element after stripping all markup). The string value of a node can be obtained using the string() function.

STYLESHEET (XSLT)

A stylesheet represents the contents of one or more stylesheet modules, consisting of a principal stylesheet module and other modules that are reachable from the principal module using <xsl:include> and <xsl:import> declarations.

STYLESHEET FUNCTION ( XSLT )

A function defined in a stylesheet using an <xsl:function> declaration. Like other functions, a stylesheet function is called using a function call in an XPath expression.

STYLESHEET MODULE ( XSLT )

A stylesheet module is defined by a single <xsl:stylesheet> or <xsl:transform> element, usually comprising the whole of an XML document; or it may be a simplified stylesheet whose root is a literal result element with an xsl:version attribute.