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A Proposed Convention for Embedding Metadata in HTML.

Reported by Stuart Weibel (weibel@oclc.org)

June 2, 1996

The following proposed convention reflects the consensus of a break-outgroup at the W3C Distributed Indexing and Searching Workshop, May28-29, 1996, concerning tagging of meta information in HTML. Thisbreak out group included representatives of the Dublin Core/WarwickFramework Metadata meetings, Lycos, Microsoft, WebCrawler, the IEEEmetadata effort, Verity Software, and the W3C.

Attendees (alphabetically):
Nick Arnett	narnett@verity.com	Mic Bowman	bowman@transarc.com
Eliot Christian	echristi@usgs.gov	Dan Connolly	conolly@w3.org
Martijn Koster	m.koster@webcrawler.com	John Kunze	jak@ckm.ucsf.edu
Carl Lagoze	lagoze@cs.cornell.edu	Michael Mauldin	fuzzy@lycos.com
Christian Mogensen	christian@vivid.com	Wick Nichols	wickn@microsoft.com
Timothy Niesen	tmn@swl.msd.ray.com	Stuart Weibel	weibel@oclc.org
Andrew Wood	woody@dstc.edu.au

1. THE PROBLEM

The problem is to identify a simple means of embedding metadata withinHTML documents without requiring additional tags or changes to browsersoftware, and without unnecessarily compromising current practices forrobot collection of data.

Given that it is judged undesirable for such embedded metadata todisplay on browser screens, any solution requires encoding informationin attribute tags rather than as container element content.

The goal was to agree on a simple convention for encoding structuredmetadata information of a variety of types (which may or may not beregistered with a central registry analogous to the Mime Typeregistry). It was judged that a registry may be a necessary feature ofthe metadata infrastructure as alternative schema are elaborated, butthat deployment in the short-term could go forward without such aregistry, especially in light of the proposed use of the LINK tag tolink descriptions to a standard schema description as described below.

2. A PROPOSED CONVENTION

The solution agreed upon is to encode schema elements in META tags, oneelement per META tag, and as many META tags as are necessary. Groupingof schema elements is achieved by a prefix schema identifier associatedwith each schema element.

The convention agreed upon is as follows:

     < META NAME    = "schema_identifier.element_name"            CONTENT = "string data"  >

Thus, a partial Dublin Core citation might be encoded as follows:

     < META NAME    = "DC.title"            CONTENT = "HTML 2.0 Specification" >             < META NAME    = "DC.author"            CONTENT = "Tim Berners-Lee" >                 < META NAME    = "DC.author"            CONTENT = "Dan Connolly" >                 < META NAME    = "DC.date"            CONTENT = "November, 1995" >                          < META NAME    = "DC.identifier"            CONTENT = "ftp://ds.internic.net/rfc/rfc1866.txt" >

And a collection of Microsoft Word metadata might be encoded as follows:

     < META NAME    = "MSW.title"            CONTENT = "W3C Indexing Work Shop Report" >             < META NAME    = "MSW.author"            CONTENT = "Wick Nichols" >                < META NAME    = "MSW.date"            CONTENT = "May 30, 1996" >

3. LINKAGE TO THE REFERENCE DESCRIPTION OF A SCHEMA

It is judged useful to provide a means for linking to the referencedefinition of a schema as well. The proposed convention for doing sois as follows:

< LINK REL = SCHEMA.schema_identifier HREF="URL" >

Thus, the reference description of one metadata scheme, the Dublin CoreMetadata Element Set, would be referenced in the LINK HREF as follows:

< LINK REL = SCHEMA.dc HREF = "http://purl.org/metadata/dublin_core" >

The description of an element could be accessed by the construction ofURL using the # token to identify a named anchor. Thus, the derivedURL below actually links to thetitle element in the referencedescription of the Dublin Core Metadata Element Set.

http://purl.org/metadata/dublin_core_elements#title

This URL would correspond to the human-readable description of thetitle element within the document by a NAME anchor such as:

<A NAME = "title"> Title </A>    The name of the work provided by the author or publisher.

While use of the LINK tag is not required for a given schema, whenused, it will make possible retrieval of the reference definition of agiven schema element, and will therefore reduce the need for a formalmetadata scheme registry. Multiple LINK tags can be used so that elements derived from multiple schemas can be referenced within a single document.

4. CONSISTENCY OF DESCRIPTION SCHEMAS

To promote consistency among resource description schemas, it issuggested that the semantics for metadata elements be related toexisting well-known schemas whenever feasible.

This page is part of the DISW 96 workshop.
Last modified: Thu Jun 20 18:20:11 EST 1996.