xsIDREFS

xsIDREFS is an XML Schema datatype that specifies a value is an IDREF, meaning it is a reference to an ID attribute declared elsewhere in the XML document. It is a member of the xs:IDREFS datatype group, which also includes xs:IDREF. The primary distinction between xs:IDREF and xs:IDREFS is that xs:IDREF represents a single ID reference, while xs:IDREFS can represent one or more ID references, separated by whitespace.

When an XML document is validated against an XML Schema that uses xs:IDREFS, the processor checks that each value conforming to this datatype is a valid reference to an element that has been declared with an ID type attribute. This ensures referential integrity within the document, similar to how foreign keys work in relational databases. The referenced ID attribute must be declared using the xs:ID datatype.

The xs:IDREFS datatype is useful for creating relationships between different parts of an XML document. For example, it could be used to link a list of tasks to the employees responsible for them, where each task might have an IDREFS attribute referencing the IDs of the assigned employees. The ability to specify multiple references in a single attribute makes it efficient for representing one-to-many or many-to-many relationships. The interpretation of these references is context-dependent and relies on the schema definition to establish the intended relationships between data elements.