XQuery 3.0: An XML Query Language

In the operator mapping tables, the term Gregorian refers to the types xs:gYearMonth, xs:gYear, xs:gMonthDay, xs:gDay, and xs:gMonth.

NaN specifies the string used for the NaN-symbol, which is used to represent the value NaN (not-a-number); the default value is the string "NaN"

A Prolog is a series of declarations and imports that define the processing environment for the module that contains the Prolog.

SequenceType matching compares the dynamic type of a value with an expected sequence type.

Static Base URI. This is an absolute URI, used to resolve relative URIs both during static analysis and during dynamic evaluation.

Within this specification, the term URI refers to a Universal Resource Identifier as defined in [RFC3986] and extended in [RFC3987] with the new name IRI.

The term XDM instance is used, synonymously with the term value, to denote an unconstrained sequence of items in the data model.

An XPath 1.0 Processor processes a query according to the XPath 1.0 specification.

XPath 1.0 compatibility mode. This component must be set by all host languages that include XPath 3.0 as a subset, indicating whether rules for compatibility with XPath 1.0 are in effect. XQuery sets the value of this component to false.

An XPath 2.0 Processor processes a query according to the XPath 2.0 specification.

An XPath 3.0 Processor processes a query according to the XPath 3.0 specification.

An XQuery 1.0 Processor processes a query according to the XQuery 1.0 specification.

An XQuery 3.0 Processor processes a query according to the XQuery 3.0 specification.

An argument to a function call is either an argument expression or an ArgumentPlaceholder ("?").

Argument expressions are evaluated with respect to DC , producing argument values.

The number of Arguments in an ArgumentList is its arity.

An atomic value is a value in the value space of an atomic type, as defined in [XML Schema 1.0] or [XML Schema 1.1].

Atomization of a sequence is defined as the result of invoking the fn:data function on the sequence, as defined in [XQuery and XPath Functions and Operators 3.0].

Available documents. This is a mapping of strings to document nodes. Each string represents the absolute URI of a resource. The document node is the root of a tree that represents that resource using the data model. The document node is returned by the fn:doc function when applied to that URI.

Available node collections. This is a mapping of strings to sequences of nodes. Each string represents the absolute URI of a resource. The sequence of nodes represents the result of the fn:collection function when that URI is supplied as the argument.

Available resource collections. This is a mapping of strings to sequences of URIs. The string represents the absolute URI of a resource which can be interpreted as an aggregation of a number of individual resources each of which has its own URI. The sequence of URIs represents the result of the fn:uri-collection function when that URI is supplied as the argument.

Available text resources. This is a mapping of strings to text resources. Each string represents the absolute URI of a resource. The resource is returned by the fn:unparsed-text function when applied to that URI.

An axis step returns a sequence of nodes that are reachable from the context node via a specified axis. Such a step has two parts: an axis, which defines the "direction of movement" for the step, and a node test, which selects nodes based on their kind, name, and/or type annotation.

A base URI declaration specifies the Static Base URI property. The Static Base URI property is used when resolving relative URI references.

In a for clause or window clause, when an expression is preceded by the keyword in, the value of that expression is called a binding sequence.

Boundary whitespace is a sequence of consecutive whitespace characters within the content of a direct element constructor, that is delimited at each end either by the start or end of the content, or by a DirectConstructor, or by an EnclosedExpr. For this purpose, characters generated by character references such as   or by CDataSections are not considered to be whitespace characters.

A boundary-space declaration sets the boundary-space policy in the static context, overriding any implementation-defined default. Boundary-space policy controls whether boundary whitespace is preserved by element constructors during processing of the query.

Boundary-space policy. This component controls the processing of boundary whitespace by direct element constructors, as described in 3.9.1.4 Boundary Whitespace.

The built-in functions supported by XQuery 3.0 are defined in [XQuery and XPath Functions and Operators 3.0].

A character reference is an XML-style reference to a [Unicode] character, identified by its decimal or hexadecimal codepoint.

A collation is a specification of the manner in which strings and URIs are compared and, by extension, ordered. For a more complete definition of collation, see [XQuery and XPath Functions and Operators 3.0].

One way to construct a sequence is by using the comma operator, which evaluates each of its operands and concatenates the resulting sequences, in order, into a single result sequence.

A computed element constructor creates an element node, allowing both the name and the content of the node to be computed.

A construction declaration sets the construction mode in the static context, overriding any implementation-defined default.

Construction mode. The construction mode governs the behavior of element and document node constructors. If construction mode is preserve, the type of a constructed element node is xs:anyType, and all attribute and element nodes copied during node construction retain their original types. If construction mode is strip, the type of a constructed element node is xs:untyped; all element nodes copied during node construction receive the type xs:untyped, and all attribute nodes copied during node construction receive the type xs:untypedAtomic.

The constructor function for a given type is used to convert instances of other atomic types into the given type. The semantics of the constructor function call T($arg) are defined to be equivalent to the expression (($arg) cast as T?).

The final part of a computed constructor is an expression enclosed in braces, called the content expression of the constructor, that generates the content of the node.

The context item is the item currently being processed.

Context item static type. This component defines the static type of the context item within the scope of a given expression.

When the context item is a node, it can also be referred to as the context node.

The context position is the position of the context item within the sequence of items currently being processed.

The context size is the number of items in the sequence of items currently being processed.

A copy-namespaces declaration sets the value of copy-namespaces mode in the static context, overriding any implementation-defined default. Copy-namespaces mode controls the namespace bindings that are assigned when an existing element node is copied by an element constructor or document constructor.

Copy-namespaces mode. This component controls the namespace bindings that are assigned when an existing element node is copied by an element constructor, as described in 3.9.1 Direct Element Constructors. Its value consists of two parts: preserve or no-preserve, and inherit or no-inherit.

Current dateTime. This information represents an implementation-dependent point in time during the processing of a query, and includes an explicit timezone. It can be retrieved by the fn:current-dateTime function. If invoked multiple times during the execution of a query, this function always returns the same result.

XQuery 3.0 operates on the abstract, logical structure of an XML document, rather than its surface syntax. This logical structure, known as the data model, is defined in [XQuery and XPath Data Model (XDM) 3.0].

A decimal format declaration adds a decimal format to the statically known decimal formats, which define the properties used to format numbers using the fn:format-number() function

decimal-separator specifies the character used for the decimal-separator-symbol; the default value is the period character (.)

Default calendar. This is the calendar used when formatting dates in human-readable output (for example, by the functions fn:format-date and fn:format-dateTime) if no other calendar is requested. The value is a string.

Default collation. This identifies one of the collations in statically known collations as the collation to be used by functions and operators for comparing and ordering values of type xs:string and xs:anyURI (and types derived from them) when no explicit collation is specified.

A default collation declaration sets the value of the default collation in the static context, overriding any implementation-defined default.

Default element/type namespace. This is a namespace URI or absent^DM30. The namespace URI, if present, is used for any unprefixed QName appearing in a position where an element or type name is expected.

Default function namespace. This is a namespace URI or absent^DM30. The namespace URI, if present, is used for any unprefixed QName appearing in a position where a function name is expected.

Default language. This is the natural language used when creating human-readable output (for example, by the functions fn:format-date and fn:format-integer) if no other language is requested. The value is a language code as defined by the type xs:language.

Default node collection. This is the sequence of nodes that would result from calling the fn:collection function with no arguments.

Default order for empty sequences. This component controls the processing of empty sequences and NaN values as ordering keys in an order by clause in a FLWOR expression, as described in 3.10.8 Order By Clause.

Default place. This is a geographical location used to identify the place where events happened (or will happen) when formatting dates and times using functions such as fn:format-date and fn:format-dateTime, if no other place is specified. It is used when translating timezone offsets to civil timezone names, and when using calendars where the translation from ISO dates/times to a local representation is dependent on geographical location. Possible representations of this information are an ISO country code or an Olson timezone name, but implementations are free to use other representations from which the above information can be derived.

Default resource collection. This is the sequence of URIs that would result from calling the fn:uri-collection function with no arguments.

The delimiting terminal symbols are: S, "!", "!=", StringLiteral, "#", "#)", "$", "%", "(", "(#", ")", "*", "+", (comma), "-", "-->", (dot), "..", "/", "//", "/>", (colon), "::", ":=", (semi-colon), "<", "<!--", "<![CDATA[", "</", "<<", "<=", "<?", "=", ">", ">=", ">>", "?", "?>", "@", BracedURILiteral, "[", "]", "]]>", "{", "|", "||", "}"

A variable value (or the context item) depends on another variable value (or the context item) if, during the evaluation of the initializing expression of the former, the latter is accessed through the module context.

digit-sign specifies the character used for the digit-sign in the picture string; the default value is the number sign character (#)

A direct element constructor is a form of element constructor in which the name of the constructed element is a constant.

Informally, document order is the order in which nodes appear in the XML serialization of a document.

The dynamic context of an expression is defined as information that is available at the time the expression is evaluated.

A dynamic error is an error that must be detected during the dynamic evaluation phase and may be detected during the static analysis phase. Numeric overflow is an example of a dynamic error.

The dynamic evaluation phase is the phase during which the value of an expression is computed.

A dynamic function call consists of a base expression that returns the function and a parenthesized list of zero or more arguments (argument expressions or ArgumentPlaceholders).

A dynamic type is associated with each value as it is computed. The dynamic type of a value may be more specific than the static type of the expression that computed it (for example, the static type of an expression might be xs:integer*, denoting a sequence of zero or more integers, but at evaluation time its value may have the dynamic type xs:integer, denoting exactly one integer.)

The effective boolean value of a value is defined as the result of applying the fn:boolean function to the value, as defined in [XQuery and XPath Functions and Operators 3.0].

The effective case of a switch expression is the first case clause that matches, using the rules given above, or the default clause if no such case clause exists.

The effective case in a typeswitch expression is the first case clause in which the value of the operand expression matches a SequenceType in the SequenceTypeUnion of the case clause, using the rules of SequenceType matching.

An empty order declaration sets the default order for empty sequences in the static context, overriding any implementation-defined default. This declaration controls the processing of empty sequences and NaN values as ordering keys in an order by clause in a FLWOR expression.

A sequence containing zero items is called an empty sequence.

If present, a version declaration may optionally include an encoding declaration. The value of the string literal following the keyword encoding is an encoding name, and must conform to the definition of EncName specified in [XML 1.0] [err:XQST0087]. The purpose of an encoding declaration is to allow the writer of a query to provide a string that indicates how the query is encoded, such as "UTF-8", "UTF-16", or "US-ASCII".

Environment variables. This is a mapping from names to values. Both the names and the values are strings. The names are compared using an implementation-defined collation, and are unique under this collation. The set of environment variables is implementation-defined and may be empty.

Two tuples T1 and T2 have equivalent grouping keys if and only if, for each grouping variable GV, the atomized value of GV in T1 is deep-equal to the atomized value of GV in T2, as defined by applying the function fn:deep-equal using the appropriate collation.

In addition to its identifying QName, a dynamic error may also carry a descriptive string and one or more additional values called error values.

An expanded QName consists of an optional namespace URI and a local name. An expanded QName also retains its original namespace prefix (if any), to facilitate casting the expanded QName into a string.

The expression context for a given expression consists of all the information that can affect the result of the expression.

An extension expression is an expression whose semantics are implementation-defined.

External functions are functions that are implemented outside the query environment.

An expression followed by a predicate (that is, E1[E2]) is referred to as a filter expression: its effect is to return those items from the value of E1 that satisfy the predicate in E2.

In a partial function application, a fixed position is an argument/parameter position for which the ArgumentList has an argument expression (as opposed to an ArgumentPlaceholder).

The first three components of the dynamic context (context item, context position, and context size) are called the focus of the expression.

A function assertion is a predicate that restricts the set of functions matched by a FunctionTest. It uses the same syntax as 4.15 Annotations.

Function coercion wraps a function^DM30 in a new function with signature the same as the expected type. This effectively delays the checking of the argument and return types until the function is invoked.

The function conversion rules are used to convert an argument value or a return value to its expected type; that is, to the declared type of the function parameter or return.

A generalized atomic type is a type which is either (a) an atomic type or (b) a pure union type

The atomized value of a grouping variable is called a grouping key.

Each grouping specification specifies one grouping variable, which refers to variable bindings in the pre-grouping tuples. The values of the grouping variables are used to assign pre-grouping tuples to groups.

grouping-separator specifies the character used for the grouping-separator-symbol, which is typically used as a thousands separator; the default value is the comma character (,)

The Higher Order Function Feature allows an expression to evaluate to a function, and allows dynamic function calls.

Ignorable whitespace consists of any whitespace characters that may occur between terminals, unless these characters occur in the context of a production marked with a ws:explicit annotation, in which case they can occur only where explicitly specified (see A.2.4.2 Explicit Whitespace Handling).

Implementation-dependent indicates an aspect that may differ between implementations, is not specified by this or any W3C specification, and is not required to be specified by the implementor for any particular implementation.

Implementation-defined indicates an aspect that may differ between implementations, but must be specified by the implementor for each particular implementation.

Implicit timezone. This is the timezone to be used when a date, time, or dateTime value that does not have a timezone is used in a comparison or arithmetic operation. The implicit timezone is an implementation-defined value of type xs:dayTimeDuration. See [XML Schema 1.0] or [XML Schema 1.1] for the range of valid values of a timezone.

In-scope attribute declarations. Each attribute declaration is identified either by an expanded QName (for a top-level attribute declaration) or by an implementation-dependent attribute identifier (for a local attribute declaration). If the Schema Aware Feature is supported, in-scope attribute declarations include all attribute declarations found in imported schemas.

In-scope element declarations. Each element declaration is identified either by an expanded QName (for a top-level element declaration) or by an implementation-dependent element identifier (for a local element declaration). If the Schema Aware Feature is supported, in-scope element declarations include all element declarations found in imported schemas.

The in-scope namespaces property of an element node is a set of namespace bindings, each of which associates a namespace prefix with a URI.

In-scope schema definitions. This is a generic term for all the element declarations, attribute declarations, and schema type definitions that are in scope during static analysis of an expression.

In-scope schema types. Each schema type definition is identified either by an expanded QName (for a named type) or by an implementation-dependent type identifier (for an anonymous type). The in-scope schema types include the predefined schema types described in 2.5.1 Predefined Schema Types. If the Schema Aware Feature is supported, in-scope schema types also include all type definitions found in imported schemas.

In-scope variables. This is a mapping from expanded QName to type. It defines the set of variables that are available for reference within an expression. The expanded QName is the name of the variable, and the type is the static type of the variable.

infinity specifies the string used for the infinity-symbol; the default value is the string "Infinity"

The initial context item is a context item that an implementation can set before processing a query begins. The query body and the prolog of every module in a query share the same initial context item.

If a variable declaration includes an expression (VarValue or VarDefaultValue), the expression is called an initializing expression. The static context for an initializing expression includes all functions, variables, and namespaces that are declared or imported anywhere in the Prolog, other than the variable being declared.

An inline function expression creates an anonymous function^DM30 defined directly in the inline function expression itself.

An item is either an atomic value, a node, or a function^DM30.

An alternative form of a node test called a kind test can select nodes based on their kind, name, and type annotation.

A lexical QName is a name that conforms to the syntax of [http://www.w3.org/TR/REC-xml-names/#NT-QName].

A module that does not contain a Query Body is called a library module. A library module consists of a module declaration followed by a Prolog.

A literal is a direct syntactic representation of an atomic value.

A main module consists of a Prolog followed by a Query Body.

MAY means that an item is truly optional.

minus-sign specifies the character used for the minus-sign-symbol; the default value is the hyphen-minus character (-, #x2D). The value must be a single character.

A module is a fragment of XQuery code that conforms to the Module grammar and can independently undergo the static analysis phase described in 2.2.3 Expression Processing. Each module is either a main module or a library module.

The module context for a given module consists of all the information that is accessible to top-level expressions in the module.

A module declaration serves to identify a module as a library module. A module declaration begins with the keyword module and contains a namespace prefix and a URILiteral.

The Module Feature allows a query Prolog to contain a Module Import and allows library modules to be created.

A module import imports the public variable declarations and public function declarations from one or more library modules into the statically known function signatures and in-scope variables of the importing module.

MUST means that the item is an absolute requirement of the specification.

MUST NOT means that the item is an absolute prohibition of the specification.

When an expression is used to specify the name of a constructed node, that expression is called the name expression of the constructor.

A node test that consists only of an EQName or a Wildcard is called a name test.

A named function is a function defined in the static context for the query. To uniquely identify a particular named function, both its name as an expanded QName and its arity are required.

A named function reference denotes a named function.

Named functions. This is a mapping from (expanded QName, arity) to function^DM30.

A namespace declaration declares a namespace prefix and associates it with a namespace URI, adding the (prefix, URI) pair to the set of statically known namespaces.

A namespace declaration attribute is used inside a direct element constructor. Its purpose is to bind a namespace prefix or to set the default element/type namespace for the constructed element node, including its attributes.

The namespace-sensitive types are xs:QName, xs:NOTATION, types derived by restriction from xs:QName or xs:NOTATION, list types that have a namespace-sensitive item type, and union types with a namespace-sensitive type in their transitive membership.

A node is an instance of one of the node kinds defined in [XQuery and XPath Data Model (XDM) 3.0].

A node test is a condition on the name, kind (element, attribute, text, document, comment, or processing instruction), and/or type annotation of a node. A node test determines which nodes contained by an axis are selected by a step.

The non-delimiting terminal symbols are: IntegerLiteral, URIQualifiedName, NCName, DecimalLiteral, DoubleLiteral, QName, "NaN", "allowing", "ancestor", "ancestor-or-self", "and", "as", "ascending", "at", "attribute", "base-uri", "boundary-space", "by", "case", "cast", "castable", "catch", "child", "collation", "comment", "construction", "context", "copy-namespaces", "count", "decimal-format", "decimal-separator", "declare", "default", "descendant", "descendant-or-self", "descending", "digit", "div", "document", "document-node", "element", "else", "empty", "empty-sequence", "encoding", "end", "eq", "every", "except", "external", "following", "following-sibling", "for", "function", "ge", "greatest", "group", "grouping-separator", "gt", "idiv", "if", "import", "in", "infinity", "inherit", "instance", "intersect", "is", "item", "lax", "le", "least", "let", "lt", "minus-sign", "mod", "module", "namespace", "namespace-node", "ne", "next", "no-inherit", "no-preserve", "node", "of", "only", "option", "or", "order", "ordered", "ordering", "parent", "pattern-separator", "per-mille", "percent", "preceding", "preceding-sibling", "preserve", "previous", "processing-instruction", "return", "satisfies", "schema", "schema-attribute", "schema-element", "self", "sliding", "some", "stable", "start", "strict", "strip", "switch", "text", "then", "to", "treat", "try", "tumbling", "type", "typeswitch", "union", "unordered", "validate", "variable", "version", "when", "where", "window", "xquery", "zero-digit"

When referring to a type, the term numeric denotes the types xs:integer, xs:decimal, xs:float, and xs:double.

A predicate whose predicate expression returns a numeric type is called a numeric predicate.

For each operator and valid combination of operand types, the operator mapping tables specify a result type and an operator function that implements the semantics of the operator for the given types.

An option declaration declares an option that affects the behavior of a particular implementation. Each option consists of an identifying EQName and a StringLiteral.

Ordering mode. Ordering mode, which has the value ordered or unordered, affects the ordering of the result sequence returned by certain expressions, as discussed in 3.11 Ordered and Unordered Expressions.

An ordering mode declaration sets the ordering mode in the static context, overriding any implementation-defined default.

An output declaration is an option declaration in the namespace "http://www.w3.org/2010/xslt-xquery-serialization"; it is used to declare serialization parameters.

A static or dynamic function call is a partial function application if one or more arguments is an ArgumentPlaceholder.

A path expression can be used to locate nodes within trees. A path expression consists of a series of one or more steps, separated by "/" or "//", and optionally beginning with "/" or "//".

pattern-separator specifies the character used for the pattern-separator-symbol, which separates positive and negative sub-pictures in a picture string; the default value is the semi-colon character (;)

per-mille specifies the character used for the per-mille-symbol; the default value is the Unicode per-mille character (#x2030)

percent specifies the character used for the percent-symbol; the default value is the percent character (%)

A positional variable is a variable that is preceded by the keyword at.

A pragma is denoted by the delimiters (# and #), and consists of an identifying EQName followed by implementation-defined content.

A predefined entity reference is a short sequence of characters, beginning with an ampersand, that represents a single character that might otherwise have syntactic significance.

Primary expressions are the basic primitives of the language. They include literals, variable references, context item expressions, constructors, and function calls. A primary expression may also be created by enclosing any expression in parentheses, which is sometimes helpful in controlling the precedence of operators.

Every axis has a principal node kind. If an axis can contain elements, then the principal node kind is element; otherwise, it is the kind of nodes that the axis can contain.

A private variable is a variable with a %private annotation. A private variable is hidden from module import, which can not import it into the in-scope variables of another module.

A private function is a function with a %private annotation. A private function is hidden from module import, which can not import it into the statically known function signatures of another module.

A public function is a function without a %private annotation. A public function is accessible to module import, which can import it into the statically known function signatures of another module.

A public variable is a variable without a %private annotation. A public variable is accessible to module import, which can import it into the in-scope variables of another module. Using %public and %private annotations in a main module is not an error, but it does not affect module imports, since a main module cannot be imported. It is a static error [err:XQST0116] if a variable declaration contains both a %private and a %public annotation, more than one %private annotation, or more than one %public annotation.

A pure union type is an XML Schema union type that satisfies the following constraints: (1) {variety} is union, (2) the {facets} property is empty, (3) no type in the transitive membership of the union type has {variety} list, and (4) no type in the transitive membership of the union type is a type with {variety} union having a non-empty {facets} property

A query consists of one or more modules.

The Query Body, if present, consists of an expression that defines the result of the query.

To resolve a relative URI $rel against a base URI $base is to expand it to an absolute URI, as if by calling the function fn:resolve-uri($rel, $base).

The node ordering that is the reverse of document order is called reverse document order.

The Schema Aware Feature permits the query Prolog to contain a schema import, and permits a query to contain a validate expression (see 3.18 Validate Expressions).

A schema import imports the element declarations, attribute declarations, and type definitions from a schema into the in-scope schema definitions. For each named user-defined simple type in the schema, schema import also adds a corresponding constructor function.

A schema type is a type that is (or could be) defined using the facilities of [XML Schema 1.0] or [XML Schema 1.1] (including the built-in types of [XML Schema 1.0] or [XML Schema 1.1]).

A sequence is an ordered collection of zero or more items.

A sequence type is a type that can be expressed using the SequenceType syntax. Sequence types are used whenever it is necessary to refer to a type in an XQuery 3.0 expression. The term sequence type suggests that this syntax is used to describe the type of an XQuery 3.0 value, which is always a sequence.

Serialization is the process of converting an XDM instance to a sequence of octets (step DM4 in Figure 1.), as described in [XSLT and XQuery Serialization 3.0].

The Serialization Feature provides means for serializing the result of a query as specified in 2.2.4 Serialization.

Setters are declarations that set the value of some property that affects query processing, such as construction mode, ordering mode, or default collation.

SHOULD means that there may exist valid reasons in particular circumstances to ignore a particular item, but the full implications must be understood and carefully weighed before choosing a different course.

A sequence containing exactly one item is called a singleton.

A singleton focus is a focus that refers to a single item; in a singleton focus, context item is set to the item, context position = 1 and context size = 1.

Document order is stable, which means that the relative order of two nodes will not change during the processing of a given query, even if this order is implementation-dependent.

The Static Typing Feature requires implementations to report all type errors during the static analysis phase.

The static analysis phase depends on the expression itself and on the static context. The static analysis phase does not depend on input data (other than schemas).

The static context of an expression is the information that is available during static analysis of the expression, prior to its evaluation.

An error that can be detected during the static analysis phase, and is not a type error, is a static error.

A static function call consists of an EQName followed by a parenthesized list of zero or more arguments.

The static type of an expression is the best inference that the processor is able to make statically about the type of the result of the expression.

Statically known decimal formats. This is a mapping from QName to decimal format, with one default format that has no visible name. Each format is used for serializing decimal numbers using fn:format-number().

Statically known collections. This is a mapping from strings to types. The string represents the absolute URI of a resource that is potentially available using the fn:collection function. The type is the type of the sequence of nodes that would result from calling the fn:collection function with this URI as its argument.

Statically known documents. This is a mapping from strings to types. The string represents the absolute URI of a resource that is potentially available using the fn:doc function. The type is the static type of a call to fn:doc with the given URI as its literal argument.

Statically known collations. This is an implementation-defined mapping from URI to collation. It defines the names of the collations that are available for use in processing queries and expressions.

Statically known default collection type. This is the type of the sequence of nodes that would result from calling the fn:collection function with no arguments.

Statically known function signatures. This is a mapping from (expanded QName, arity) to function signature^DM30.

Statically known namespaces. This is a mapping from prefix to namespace URI that defines all the namespaces that are known during static processing of a given expression.

A step is a part of a path expression that generates a sequence of items and then filters the sequence by zero or more predicates. The value of the step consists of those items that satisfy the predicates, working from left to right. A step may be either an axis step or a postfix expression.

The string value of a node is a string and can be extracted by applying the fn:string function to the node.

Substitution groups are defined in [XML Schema 1.0] and [XML Schema 1.1] Part 1. Informally, the substitution group headed by a given element (called the head element) consists of the set of elements that can be substituted for the head element without affecting the outcome of schema validation.

A sequence type A is a subtype of a sequence type B if the judgement subtype(A, B) is true.

The use of a value whose dynamic type is derived from an expected type is known as subtype substitution.

Each rule in the grammar defines one symbol, using the following format:

Whitespace and Comments function as symbol separators. For the most part, they are not mentioned in the grammar, and may occur between any two terminal symbols mentioned in the grammar, except where that is forbidden by the /* ws: explicit */ annotation in the EBNF, or by the /* xgc: xml-version */ annotation.

The target namespace of a module is the namespace of the objects (such as elements or functions) that it defines.

A terminal is a symbol or string or pattern that can appear in the right-hand side of a rule, but never appears on the left-hand side in the main grammar, although it may appear on the left-hand side of a rule in the grammar for terminals.

A tuple is a set of zero or more named variables, each of which is bound to a value that is an XDM instance.

A tuple stream is an ordered sequence of zero or more tuples.

Each element node and attribute node in an XDM instance has a type annotation ( described in [XQuery and XPath Data Model (XDM) 3.0]. ) The type annotation of a node is a reference to an XML Schema type.

A variable binding may be accompanied by a type declaration, which consists of the keyword as followed by the static type of the variable, declared using the syntax in 2.5.4 SequenceType Syntax.

A type error may be raised during the static analysis phase or the dynamic evaluation phase. During the static analysis phase, a type error occurs when the static type of an expression does not match the expected type of the context in which the expression occurs. During the dynamic evaluation phase, a type error occurs when the dynamic type of a value does not match the expected type of the context in which the value occurs.

Under certain circumstances, an atomic value can be promoted from one type to another. Type promotion is used in evaluating function calls (see 3.1.5.1 Evaluating Static and Dynamic Function Calls ), order by clauses (see 3.10.8 Order By Clause), and operators that accept numeric or string operands (see B.2 Operator Mapping).

The Typed Data Feature permits an XDM instance to contain element node types other than xs:untyped and attributes node types other than xs:untypedAtomic.

The typed value of a node is a sequence of atomic values and can be extracted by applying the fn:data function to the node.

User defined functions are functions that contain a function body, which provides the implementation of the function as an XQuery expression.

In the data model, a value is always a sequence.

A variable reference is an EQName preceded by a $-sign.

Variable values. This is a mapping from expanded QName to value. It contains the same expanded QNames as the in-scope variables in the static context for the expression. The expanded QName is the name of the variable and the value is the dynamic value of the variable, which includes its dynamic type.

A version declaration can identify the applicable XQuery syntax and semantics for a module, as well as its encoding.

In addition to static errors, dynamic errors, and type errors, an XQuery 3.0 implementation may raise warnings, either during the static analysis phase or the dynamic evaluation phase. The circumstances in which warnings are raised, and the ways in which warnings are handled, are implementation-defined.

A whitespace character is any of the characters defined by [http://www.w3.org/TR/REC-xml/#NT-S].

A window is a sequence of consecutive items drawn from the binding sequence.

xs:anyAtomicType is an atomic type that includes all atomic values (and no values that are not atomic). Its base type is xs:anySimpleType from which all simple types, including atomic, list, and union types, are derived. All primitive atomic types, such as xs:decimal and xs:string, have xs:anyAtomicType as their base type.

xs:dayTimeDuration is derived by restriction from xs:duration. The lexical representation of xs:dayTimeDuration is restricted to contain only day, hour, minute, and second components.

xs:error is a simple type with no value space, defined in [XML Schema 1.1]. In implementations that support XML Schema 1.1, it can be used in the 2.5.4 SequenceType Syntax to raise errors.

xs:untyped is used as the type annotation of an element node that has not been validated, or has been validated in skip mode.

xs:untypedAtomic is an atomic type that is used to denote untyped atomic data, such as text that has not been assigned a more specific type.

xs:yearMonthDuration is derived by restriction from xs:duration. The lexical representation of xs:yearMonthDuration is restricted to contain only year and month components.

zero-digit specifies the character used for the zero-digit-symbol; the default value is the digit zero (0). This character must be a digit (category Nd in the Unicode property database), and it must have the numeric value zero. This attribute implicitly defines the Unicode character that is used to represent each of the values 0 to 9 in the final result string: Unicode is organized so that each set of decimal digits forms a contiguous block of characters in numerical sequence.