W3C proposes XML identifiers

The W3C (World Wide Web Consortium) on Tuesday proposed XML:ID as a standard way to uniquely identify parts of an XML document, promising the specification would make the work of XML authors easier.

"It's going to simplify their life a lot," said Philippe Le Hégaret, the W3C's architecture domain leader. "They will be able to use identifiers more reliably without having to care what the XML parser is going to support."

The way it is now, XML authors can identify parts of a document using a separate document like a schema or DTD (document type definition). That can lead to trouble if an XML parser can't find or read a schema.

XML authors also currently use internal mechanisms for identifiers, but those also run into problems.

"Some specifications, notably SOAP (Simple Object Access Protocol) forbid an internal subset, and processing the external subset is optional for conformant XML processors, leaving no guarantee that all consumers of the XML document will be able to successfully recognize the identifiers," the proposed recommendation reads.

Unique identifiers are useful, for example, when an author wants to apply CSS (Cascading Style Sheets) or XSLT (Extensible Stylesheet Language Transformations) effects to an individual element within a document, like a particular table or form.

The "proposed recommendation" status of XML:ID is the penultimate in the W3C's four-part recommendation process. The group is accepting comments through Aug. 26.