Metadata is information about information - for example, a catalogue record for a book. Metadata is stored in the head of web resources and is accessed by machines, especially those associated with search engines. Metadata does not normally appear as part of the resource itself.
Metadata, information about information, may contain functionality, as in the case of a resource required to be refreshed at regular intervals, for instance because it contains information that is updated minute by minute - eg from a web camera or other changing data source.
<meta name="author" content="mary
Smith">
<meta name="http-equiv="refresh""
content="2;url=http://www.whatshappening.com/datastore.html">
<meta name="author" content="mary
Smith">
Metadata is being used more and more to provide users and user agents with information for discovery, and in the accessibility context, hopefully to help transform the content into accessible forms for individual users. A number of international bodies are working on metadata standards for accessibility. Metadata can be used for matching, to ensure the user agent can handle the content, or that it can be transformed by an application so that the user agent can handle it. In addition, users can work with the metadata of a site instead of directly with the content. An example is a user working on a site map generated by an agent, avoiding the problems of navigation present in the site itself. It is anticipated that the utility of metadata will increase with increased use of XML.
See, in particular:
instead of embedding metadata in SVG, can it be linked?
You can link it using something like Annotea (easiest to play with in Amaya as annotations) - an out of line linking technology, or you can include a single "see also" piece of metadata pointing to more. I don't think there is a purpose-built linking construct for metadata. (Don't take my word on that)
Last updated: 8 March 2002