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TEI Overlapping Markup SIG meeting in Baltimore

Report of TEI Overlapping Markup SIG meeting in Baltimore

Date:         Wed, 24 Nov 2004 13:55:11 -0500
Sender:       TEI Overlapping Markup SIG discussion list <TEI-OL-SIG@LISTSERV.BROWN.EDU>
From:         Dot Porter <dporter@UKY.EDU>
Subject:      Report of Overlapping Markup SIG meeting in Baltimore

Hello Overlapping Markup Listserv,

I just sent this announcement to the general TEI listserv, but I wanted to post it here as well and invite your thoughts and comments. I would be especially interested in discussing some real-life examples of overlapping markup - the examples from the P4 chapter are quite short and not very complex. Lou had mentioned in a previous message the possibility of setting up a Wiki, though which we could trade examples and discussion. Are others interested in this approach? Please let me know, and if there is sufficient interest I'll set one up for us.

If Andreas Witt is on the listserv, I'd like him to say a few words (or more!) about the chapter for P5.

Thanks, Dot

Hello TEI Listserv,

Here is a brief report of the Overlapping Markup SIG in Baltimore, 23 October [2004]. You can also view the report, with examples, at (the main SIG website is at

Please let me know if you have instances of overlapping markup and you would like to see if the approach described in this report will address your concerns. I am considering setting up a Wiki through which the TEI community can post examples and discuss the advantages and drawbacks of various approaches.

Note that the work of this SIG is not to rewrite the chapter on Overlapping Markup for P5, although we do hope to work together with the author, Andreas Witt.

Feedback is welcomed and encouraged!


Overlapping Markup SIG Minutes 23 October, 2004 Dot Porter November 12, 2004

Seven in attendence.

Approach: At last year's meeting (see the minutes), we had discussed creating a web site to explain in some detail many different approaches to overlapping markup. This year, we discussed some approaches that are currently in use by those of us in the SIG: the use of milestone elements and Just In Time Trees (JITTS). The traditional problem with using milestone elements extensively to deal with overlapping markup is that existing support languages (XPath, XSLT) cannot deal with non-content (that is, text between two milestone elements acting as the beginning and end tags). However, Alex Dekhtyar and Emil Iacob at the University of Kentucky have been working on an extension of XPath (Extended XPath, or EXPath) that can search overlapping encodings represented in a GODDAG. The GODDAG can be stored in an XML file with milestones (plus a set of DTDs, one per hierarchy) or in separate files: one XML file per hierarchy. In fact, the storage method is not important as long as there are parsers for GODDAG. The GODDAG implementation provides DOM-like API which can be used as well by an XML editor. They have begun working on an extension of XSLT as well. Patrick Durusau also cited a paper presented at the 2004 Extreme Markup Conference by Steven DeRose, Markup Overlap: A Review and a Horse. In this paper, DeRose outlines a system of milestone elements similar to that already implemeneted at the University of Kentucky, which he calls clix (not to be confused with Constraint Language in XML (CLIX)).

The SIG proposes to investigate the possibility of implementing within TEI a system for dealing with overlapping markup through a system of milestone elements based on clix, JITTS, and the EXPath and EXSLT support being developed at the University of Kentucky.

  • Provide several examples on the OM SIG website and invite TEI users to comment and criticize the approach
  • Invite examples of overlapping markup from the user community
  • Finally, make a recommendation to the TEI editors — either to look into making the milestone approach an integrated part of P5 (if it appears to handle most instances of OM), or not.


Steven DeRose, Markup Overlap: A Review and a Horse


Extended XPath language (EXPath)

Prepared by Robin Cover for The XML Cover Pages archive. General references in "Markup Languages and (Non-) Hierarchies."

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