G Glossary (Non-Normative)

EnumerationType

An EnumerationType accepts a fixed set of string values.

Gregorian

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

NaN

NaN is the string used to represent the double value NaN (not-a-number); the default value is the string "NaN"

SequenceType matching

SequenceType matching compares a value with an expected sequence type.

Static Base URI

Static Base URI. This is an absolute URI, used to resolve relative URI references.

URI

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.

XDM instance

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

XPath 1.0 compatibility mode

XPath 1.0 compatibility mode. This value is true if rules for backward compatibility with XPath Version 1.0 are in effect; otherwise it is false.

anonymous function

An anonymous function is a function item with no name. Anonymous functions may be created, for example, by evaluating an inline function expression or by partial function application.

argument expression

An argument to a function call is either an argument expression or an ArgumentPlaceholder (?); in both cases it may either be supplied positionally, or identified by a name (called a keyword).

arity range

A function definition has an arity range, which is a range of consecutive non-negative integers. If the function definition has M required parameters and N optional parameters, then its arity range is from M to M+N inclusive.

array

An array is a function item that associates a set of positions, represented as positive integer keys, with values.

arrow operator

An arrow operator applies a function to the value of an expression, using the value as the first argument to the function.

associated value

The value associated with a given key is called the associated value of the key.

atomic value

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

Atomization of a sequence is defined as the result of invoking the fn:data function, as defined in Section 2.4 fn:data FO31.

available documents

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 item collections

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

available text resources

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.

available uri collections

Available URI 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.

axis step

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.

built-in function

Built-in functions are function definitions that are always present in the static context by virtue of rules in the host language; they will typically include the functions specified in [XQuery and XPath Functions and Operators 4.0].

coercion rules

The coercion rules are rules used to convert a supplied value to a required type, for example when converting an argument of a function call to the declared type of the function parameter.

collation

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 Section 5.3 Comparison of strings FO31.

comma operator

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.

constructor function

The constructor function for a given type is used to convert instances of other simple 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?).

content expression

In an enclosed expression, the optional expression enclosed in curly braces is called the content expression.

context item

The context item is the item currently being processed.

context item static type

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

context node

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

context position

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

context size

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

current dateTime

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

data model

XPath 4.0 operates on the abstract, logical structure of an XML document or JSON object, rather than its surface syntax. This logical structure, known as the data model, is defined in [XQuery and XPath Data Model (XDM) 3.1].

decimal-separator

decimal-separator is the character used to separate the integer part of the number from the fractional part, both in the picture string and in the formatted number; the default value is the period character (.)

default URI collection

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

default calendar

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

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.

default collection

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

default element namespace

Default element namespace. This is a namespace URI or absentDM31. The namespace URI, if present, is used for any unprefixed QName appearing in a position where an element name is expected.

default function namespace

Default function namespace. This is either a namespace URI, or absentDM31. The namespace URI, if present, is used for any unprefixed QName appearing in a position where a function name is expected.

default language

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 place

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 type namespace

Default type namespace. This is a namespace URI or absentDM31. The namespace URI, if present, is used for any unprefixed QName appearing in a position where a type name is expected.

delimiting terminal symbol

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

digit

digit is a character used in the picture string to represent an optional digit; the default value is the number sign character (#)

document order

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

dynamic context

The dynamic context of an expression is defined as information that is needed for the dynamic evaluation of an expression.

dynamic error

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.

dynamic evaluation phase

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

dynamic function call

A dynamic function call is an expression that is evaluated by calling a function item, which is typically obtained dynamically.

dynamic function call

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).

dynamic type

Every value matches one or more sequence types. A value is said to have a dynamic type T if it matches (or is an instance of) the sequence type T.

dynamically known function definitions

Dynamically known function definitions. This is a set of function definitions. It includes the statically known function definitions as a subset, but may include other function definitions that are not known statically.

effective boolean value

The effective boolean value of a value is defined as the result of applying the fn:boolean function to the value, as defined in Section 7.3.1 fn:boolean FO31.

empty sequence

A sequence containing zero items is called an empty sequence.

enclosed expression

An enclosed expression is an instance of the EnclosedExpr production, which allows an optional expression within curly braces.

entry

Each key / value pair in a map is called an entry.

environment variables

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.

error value

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

expanded QName

An expanded QName is a triple: its components are a prefix, a local name, and a namespace URI. In the case of a name in no namespace, the namespace URI and prefix are both absent. In the case of a name in the default namespace, the prefix is absent.

exponent-separator

exponent-separator is the character used to separate the mantissa from the exponent in scientific notation both in the picture string and in the formatted number; the default value is the character (e).

expression context

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

external function

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

filter expression

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.

fixed position

In a partial function application, a supplied parameter is any parameter other than one for which the ArgumentList includes a placeholder.

focus

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

function coercion

Function coercion wraps a function item in a new function whose signature is the same as the expected type. This effectively delays the checking of the argument and return types until the function is called.

function definition

A function definition contains information used to evaluate a static function call, including the name, parameters, and return type of the function.

function item

A function item is an item that can be called using a dynamic function call.

generalized atomic type

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

grouping-separator

grouping-separator is the character typically used as a thousands separator, both in the picture string and in the formatted number; the default value is the comma character (,)

guarded

An expression E is said to be guarded by some governing condition C if evaluation of E is not allowed to fail with a dynamic error except when C applies.

host-language

A host language for XPath is a language or specification that incorporates XPath as a sublanguage and that defines how the static and dynamic context for evaluation of XPath expressions are to be established.

ignorable whitespace

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

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

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

implicit timezone

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 Section 3.2.7.3 Timezones XS1-2 or Section 3.3.7 dateTime XS11-2 for the range of valid values of a timezone.

in-scope attribute declarations

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).

in-scope element declarations

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).

in-scope namespaces

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

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 type

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 3.1 Predefined Schema Types.

in-scope variables

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

infinity is the string used to represent the double value infinity (INF); the default value is the string "Infinity"

inline function expression

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

item

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

item type

An item type is a type that can be expressed using the ItemType syntax, which forms part of the SequenceType syntax. Item types match individual items.

item type aliases

Item type aliases. This is a mapping from expanded QName to ItemTypes.

kind test

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

lexical QName

A lexical QName is a name that conforms to the syntax of the QName production

literal

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

map

A map is a function that associates a set of keys with values, resulting in a collection of key / value pairs.

may

MAY means that an item is truly optional.

member

The values of an array are called its members.

minus-sign

minus-sign is the single character used to mark negative numbers; the default value is the hyphen-minus character (#x2D).

must

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

must not

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

name test

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

named function reference

A named function reference is an expression (written name#arity) which evaluates to a function item.

namespace-sensitive

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.

node

A node is an instance of one of the node kinds defined in Section 6 Nodes DM31.

node test

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.

non-delimiting terminal symbol

The non-delimiting terminal symbols are: IntegerLiteral, URIQualifiedName, NCName, DecimalLiteral, DoubleLiteral, QName, "ancestor", "ancestor-or-self", "and", "array", "as", "attribute", "cast", "castable", "child", "comment", "descendant", "descendant-or-self", "div", "document-node", "element", "else", "empty-sequence", "enum", "eq", "every", "except", "following", "following-sibling", "for", "function", "ge", "gt", "idiv", "if", "in", "instance", "intersect", "is", "item", "le", "let", "lt", "map", "member", "mod", "namespace", "namespace-node", "ne", "node", "of", "or", "otherwise", "parent", "preceding", "preceding-sibling", "processing-instruction", "record", "return", "satisfies", "schema-attribute", "schema-element", "self", "some", "text", "then", "to", "treat", "union", "with"

numeric

When referring to a type, the term numeric denotes the types xs:integer, xs:decimal, xs:float, and xs:double which are all member types of the built-in union type xs:numeric.

operator function

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.

partial function application

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

partially applied function

A partially applied function is a function created by partial function application.

path expression

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

pattern-separator is a character used to separate positive and negative sub-pictures in a picture string; the default value is the semi-colon character (;)

per-mille

per-mille is the character used both in the picture string and in the formatted number to indicate that the number is written as a per-thousand fraction; the default value is the Unicode per-mille character (#x2030)

percent

percent is the character used both in the picture string and in the formatted number to indicate that the number is written as a per-hundred fraction; the default value is the percent character (%)

primary expression

Primary expressions are the basic primitives of the language. They include literals, variable references, context item expressions, 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.

principal node kind

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.

pure union type

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

resolve

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).

reverse document order

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

same key

Two atomic values K1 and K2 have the same key value if op:same-key(K1, K2) returns true, as specified in Section 17.1.1 op:same-key FO31

schema type

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).

sequence

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

sequence type

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 XPath 4.0 expression. The term sequence type suggests that this syntax is used to describe the type of an XPath 4.0 value, which is always a sequence.

singleton

A sequence containing exactly one item is called a singleton.

singleton focus

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.

stable

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

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).

static context

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

static error

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

static function call

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

static type

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.

static typing feature

The Static Typing Feature is an optional feature of XPath that provides support for static semantics, and requires implementations to detect and report type errors during the static analysis phase.

statically known collections

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 items that would result from calling the fn:collection function with this URI as its argument.

statically known documents

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

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 expressions.

statically known decimal formats

Statically known decimal formats. This is a mapping from QNames to decimal formats, with one default format that has no visible name, referred to as the unnamed decimal format. Each format is available for use when formatting numbers using the fn:format-number function.

statically known default collection type

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

statically known function definitions

Statically known function definitions. This is a set of function definitions.

statically known namespaces

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.

step

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.

string value

The string value of a node is a string and can be extracted by applying the Section 2.3 fn:string FO31 function to the node.

substitution group

Substitution groups are defined in Section 2.2.2.2 Element Substitution Group XS1-1 and Section 2.2.2.2 Element Substitution Group XS11-1. 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.

subtype

Given two sequence types or item types, the rules in this section determine if one is a subtype of the other. If a type A is a subtype of type B, it follows that every value matched by A is also matched by B.

subtype substitution

The use of a value that has a dynamic type that is a subtype of the expected type is known as subtype substitution.

symbol

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

symbol ::= expression
symbol separators

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.

terminal

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.

type alias

A type alias is an expanded QName that is mapped to an ItemType in the item type aliases of the static context.

type annotation

Each element node and attribute node in an XDM instance has a type annotation (described in Section 2.7 Schema Information DM31). The type annotation of a node is a reference to an XML Schema type.

type error

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.

type promotion

Under certain circumstances, an atomic value can be promoted from one type to another. Type promotion is used in evaluating function calls (see 4.4.1.1 Static Function Call Syntax) and operators that accept numeric or string operands (see B.2 Operator Mapping).

typed value

The typed value of a node is a sequence of atomic values and can be extracted by applying the Section 2.4 fn:data FO31 function to the node.

value

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

variable reference

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

variable values

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.

warning

In addition to static errors, dynamic errors, and type errors, an XPath 4.0 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.

whitespace

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

wildcard-matches

In these rules, if M and N are NameTests, then M wildcard-matches N is true if every name that matches M also matches N.

xs:anyAtomicType

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

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

xs:error is a simple type with no value space. It is defined in Section 3.16.7.3 xs:error XS11-1 and can be used in the 3.4 Sequence Types to raise errors.

xs:untyped

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

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

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

zero-digit is the character used to represent the digit zero; the default value is the Western digit zero (#x30). This character must be a digit (category Nd in the Unicode property database), and it must have the numeric value zero. This property implicitly defines the ten Unicode characters that are used to represent the values 0 to 9: Unicode is organized so that each set of decimal digits forms a contiguous block of characters in numerical sequence. Within the picture string any of these ten character can be used (interchangeably) as a place-holder for a mandatory digit. Within the final result string, these ten characters are used to represent the digits zero to nine.