The origins of ODD

I’m moving house this week, which involves packing up thirty years of accumulated junk of various sorts. As a result, every now and then I stumble upon some long lost historic document, like this one. It dates from a lunch that Michael Sperberg-McQueen and I enjoyed at the Lido restaurant Bergen in November 1991. This being a family restaurant, it was equipped with paper table cloths and wax crayons, Norwegian kids for the use of, which Michael and I were quick to reappropriate to our immediate needs, namely some kind of visual representation of the production system we wanted to create for the editing and processsing of the TEI Guidelines, version P2. We knew we were going to write and edit it in some version of TEI SGML; we had faith that anything in SGML could be transformed into anything else. We just had to work out how, and what.

P1 had been produced by some devious hackery that only Michael understood, and more critically which only ran on the mainframe at UIC; we wanted something that would be platform (hardware and software) independe nt. Such was the promise of TEI SGML, after all. Somewhat to our horror, the only reasonable high level programming language in which we were both reasonably competent and for which there were decent implementations on all the machines we collectively used (IBM CMS, VAX VMS, IBM PC, Macintosh…) seemed to be a now largely-forgotten string handling language called Macro Spitbol, so we decided that our production system (what nowadays we’d call a work flow) would have to be written in that. But of course the heart of everything would be a nice author-friendly TEI SGML dialect, for which we optimistically coined the acronym ODD: One Document Does-it-all. ODD files would be parsed by an SGML parser, and its output filtered through a variety of Spitbol processors to create other formats. And that, more or less, is what we did.

On this schematic you can see the basic idea in blue. The big blue circle is the ODD format, from which are generated canonical TEI files (with extension .TIN (for Tiny) or .TEI), RL files (extension .TD), and DTD files, the three little blue boxes. DTD files are of course SGML DTD files, which ois why you see a green line going back from them to validate individual ODD files (I dont know why it’s labelled LB though). “Tiny” files would use a subset of the TEI Lite schema defined back in 1988; RL (later renamed .REF) files would use the TEI vocabulary Michael had developed for reference documentation of individual elements (“TD” for tag documentation). Down the middle you see a list of TLAs in blue which I think must have been attempts to decide on a name for the format (WEB, Joe, LAM, RDF, CSP…), though what they expand to I really don’t remember – what a pity we didn’t choose RDF. Or not. And over on the left in red you see some notes which eventually became the canonical structure of the TEI Guidelines: there is a chapter about the “blort”, containing prose paragraphs; there is a documentation element referencing the blort tag, and there is a parameter entity reference which pulls in the definitions for the blort chapter.

What happened next? Well, we did set up a workflow more or less on this model, and we did use three separate filters written in macro Spitbol (mostly by Michael) which turned our ODD SGML into two flavours of straightforward TEI-lite-like SGML, which we called “P2X” and “REF” and also generated SGML DTD fragments. After experimenting with a generic filter called “tf” (also in Spitbol) to translate the generated TEI files into LaTeX, and dallying with a Canadian tool called Omnimark, we finally settled on a rather swish transformation engine called Balise, which was produced by a French company called AIS. Either way we were able to print the fascicles of P2 in something that not only looked quite nice but also looked just the same whether I printed it in Oxford, or Michael in Chicago. Except for the paper size, of course: ain’t standardisation a marvellous thing.

And what happened to ODD? It turned out to be quite a good idea. We gave a presentation about it at the ACH-ALLC conference in 1994, though I cannot remember what we said and we never got round to writing it up. Michael developed the ideas in the “tag documentation” part quite extensively, and (I believe) used them also in his next job working for the W3C, but the TEI’s ODD stayed more or less unchanged until work started on the TEI’s XML reincarnation, at which time the whole system was re-imagined and redesigned as the lean mean generic schema generation system we know and love today. But that’s another story.


Laisser un commentaire

Votre adresse de messagerie ne sera pas publiée. Les champs obligatoires sont indiqués avec *