W3C's HTML Working Group has released a first public Working Draft specification for HLink: Link Recognition for the XHTML Family. The HLink module defined in the specification "provides XHTML Family Members with the ability to specify which attributes of elements represent hyperlinks, and how those hyperlinks should be traversed, and extends XLink use to a wider class of languages than those restricted to the syntactic style allowed by XLink." Normative 'Appendix A' documents three implementations defined in terms of XML DTD, RELAX NG, and W3C XML Schema. The HLink module defined in the WD uses the XML Namespaces identifier http://www.w3.org/2002/06/hlink. The new markup that can be used to describe links in XHTML Family members "consists of two elements; they are used to associate properties with markup elements and attributes to describe how they behave as links. Many of the descriptive properties are taken from XLink, but with additions to support the behaviour of links in XHTML. The <hlinks> element exists only to be a root element for a document containing only <hlink> elements. The empty element <hlink> is used to identify an element and/or attributes within a namespace, and associates properties with them to specify how the element should be treated as a link, or how the attributes contribute to an element that is a link. HLink may be used in two ways: (1) the first is by putting the <hlink>s in the <head> [element]; (2) the other is by putting them in a separate resource, and referring to that resource by a hlink:definition URI attribute on the root element of the document. At the time of publication, the Working Group believed there were no patent disclosures relevant to the HLink specification.
Bibliographic information: HLink: Link Recognition for the XHTML Family. W3C Working Draft 13-September-2002. Edited by Steven Pemberton (CWI/W3C) and Masayasu Ishikawa (W3C). Version URL: http://www.w3.org/TR/2002/WD-hlink-20020913. Latest version URL: http://www.w3.org/TR/hlink.
Comment from Joe English: "Initial impression: This [WD] looks OK. It finally reinvents architectural forms in a way that's usable in XML. XLink started to do this, but the omission of any kind of attribute renaming facility and the lack of a reliable attribute value defaulting scheme made XLink inflexible and difficult to use, as Steve Pemberton's message convincingly described. The 'hlink' declaration scheme solves both those problems... [LB: 'are these arc forms renamed and slightly weakened such that what we end up with is more complicated and less powerful...?'] The 'hlink:hlink' element does all that's required to endow arbitrary host vocabulary elements with XLink semantics, and it does so without using all the PIs, NOTATION declarations, and levels of indirection required by the HyTime 2 AFDR. This looks a lot simpler... OK, so it relies on XML Namespaces. This is not, in my eyes, a big deal; it's one of the few things that XML namespaces are actually good for..." [see "Architectural Forms and SGML/XML Architectures"]
Principal references:
- HLink: Link Recognition for the XHTML Family
- "Announcing HLink: Rationale." Posting from Steven Pemberton to the 'www-tag@w3.org' list September 13, 2002. See related postings from Tim Bray, Simon St.Laurent, Norman Walsh, Paul Grosso, and others.
- Comments on the WD: send email to www-html-editor@w3.org
- Archives for 'www-html-editor@w3.org'
- Public discussion: send email to www-html@w3.org.
- Mail archives for 'www-html'
- XML Linking Language (XLink) Version 1.0. W3C Recommendation 27-June-2001.
- W3C HyperText Markup Language (HTML) Home Page
- W3C HTML Activity Statement
- See also: "Architectural Forms and SGML/XML Architectures" - Main reference page.
