Name
xsd:ID — Definition of unique identifiers
Synopsis
<xsd:simpleType name="ID” id="ID"> <xsd:restriction base="xsd:NCName"/> </xsd:simpleType>
Derived from
xsd:NCName
Primary
xsd:string
Known subtypes
None
Data parameters (facets)
enumeration
, length
,
maxLength
, minLength
,
pattern
Description
The purpose of the xsd:ID
datatype is to define
unique identifiers that are global to a document and emulate the ID
attribute type available in the XML DTDs.
Unlike their DTD counterparts, W3C XML Schema ID datatypes can be applied to not only attributes but also simple element content.
For both attributes and simple element content, the lexical domain of
these datatypes is the lexical domain of XML nonqualified names
(xsd:NCName
).
Identifiers defined using this datatype are global to a document and provide a way to uniquely identify their containing element, whatever its type and name is.
The constraint added by this datatype, beyond the
xsd:NCName
datatype from which it is derived, is
that the values of all the attributes and elements that have an ID
datatype in a document must be unique.
Note that the behavior of this datatype depends on whether the RELAX NG implementation supports RELAX NG DTD compatibility datatype library, in which case, the uniqueness of the identifiers will be checked. This datatype can be used both for elements and for defining multiple type assignment to attributes defined as ID, depending on their location in the schema.
Restrictions
Applications that need to maintain a level ...
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