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xhtml+heml profile: schema and transformations

From: Bruce Robertson <broberts@mta.ca>
Date: Thu, 12 Jun 2003 10:40:12 -0300
Message-ID: <1055425212.3ee882bcd604d@webmail.mta.ca>
To: www-html@w3.org

The Historical Event Markup and Linking project (Heml: http://heml.mta.ca) has a
working xhtml profile language which might be of interest to those who subscribe
to this list. A sample document, suitably transformed, is available at: 


Heml defines a lightweight XML language (see
http://heml.mta.ca/heml-cocoon/schemata) that associates web resources with
historical events described in terms of chronology, location, participants and
keywords. The project further provides a webapp to transform conforming
documents into hyperlinked SVG graphical timelines, historical maps, etc. It
also has a working facility to aggregate valid markup.

The xhtml+heml profile schema permits the occurence of heml:Event elements
within xhtml text blocks. The xhtml+heml transformation engine adds a sidebar
with links to maps and timelines generated from the document's heml elements. We
imagine this language to be useful in informal documents with an historical
dimension (such as family histories), in course notes, and for retrofitting into
existing web pages.

Some implementation notes:

1. A browser with the Adobe SVG Viewer provides the richest experience. Browsers
without SVG are passed static images. 

2. The xhtml+heml schema was written by rewriting the published xhtml.xsd file
to include heml elements. It would be more elegant to use XML Schema's
<xs:redefine> syntax, and in fact this works nicely and validates with Xerces.
Unfortunately, it seems no XML editor groks this approach yet.

3. The webapp can be used as a (slow) proxy. If you want to view your own valid
xhtml+heml documents without installing the webapp, pass them to

Comments, criticism, etc. are welcome.

Bruce Robertson, 
Dept. of Classics, Mount Allison University
Received on Thursday, 12 June 2003 09:39:42 UTC

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