xs:IDREFS — Definition of lists of references to unique identifiers.
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>
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.
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 to
xs:IDREFS
).
<xs:element name="book"> <xs:complexType> <xs:sequence> <xs:element name="isbn" type="xs:int"/> <xs:element name="title" type="xs:string"/> <xs:element name="author-ref"> <xs:complexType> <xs:attribute name="ref" type="xs:IDREF" use="required"/> </xs:complexType> </xs:element> <xs:element name="character-refs" type="xs:IDREFS"/> </xs:sequence> <xs:attribute name="identifier" type="xs:ID" use="required"/> </xs:complexType> </xs:element>
3.138.113.188