xs:IDREF

Construct an IDREF value from an item value.

Related Syntax Constructs

The following construct(s) refer to this construct:

[ Syntax | Description | Argument | Examples ]

Syntax

xs:IDREF(item $value) => IDREF

Description

This is a constructor function that takes an item value as argument and returns a value of type xs:IDREF. If the argument is a literal, then the literal must be a valid lexical form of its type.

As specified in the respective section of the W3C recommendation XML Schema Part 2: Datatypes, a value of type xs:IDREF denotes an ID attribute type, as defined in the XML 1.0 recommendation. It is derived from the type xs:NCName and the lexical form of xs:IDREF is the set of all strings that match the production of NCName.

For compatibility reasons values of this type should only be used as attribute values.

Argument

$value	item value

Examples

The following queries generate valid values of type xs:IDREF
```
xs:IDREF("_header")
```
```
xs:IDREF("R2D2")
```
The following queries generate invalid values of type xs:IDREF
```
xs:IDREF("-header")
```
```
xs:IDREF("1A")
```