Name
xs:IDREFS — Definition of lists of references to unique identifiers.
Derived from:
xs:IDREF
Primary:
none
Known subtypes:
none
Facets:
xs:enumeration, xs:length, xs:maxLength, xs:minLength, xs:whiteSpace
<xs:simpleType name="IDREFS" id="IDREFS">
<xs:restriction>
<xs:simpleType>
<xs:list>
<xs:simpleType>
<xs:restriction base="xs:IDREF"/>
</xs:simpleType>
</xs:list>
</xs:simpleType>
<xs:minLength value="1"/>
</xs:restriction>
</xs:simpleType>Description
xs:IDREFS is derived as a list from
xs:IDREF and, thus, represents
whitespace-separated lists of references to identifiers defined using
the ID datatype.
The lexical space of xs:IDREFS is the lexical
space of a list of xs:NCName values with a minimum
length of one element (xs:IDREFS cannot be empty
lists).
xs:IDREFS emulates the
xs:IDREFS attribute type of the XML DTDs, even
though it can be used to define simple content elements as well as
attributes.
Restrictions
Applications that need to maintain a level of compatibility with DTDs should not use this datatype for elements but should reserve it for attributes.
The lexical domain (lists of xs:NCName) of this
datatype doesn’t allow definition of lists of
numerical key references or references containing whitespaces.
Although the W3C XML Schema provides another mechanism to define
unique, key, and key reference constraints (using the
xs:unique, xs:key, and
xs:keyref elements) when more flexibility is needed, this mechanism doesn’t provide any alternative for lists of key references (similar ...