Eve Maler has a little history and analysisof some on-their-way -to-being-forgotten document formats and how they relate to the current debate about word processing formats. If you want to know a bit more about SGML vs the ill-fated ODA, as well as the currently-hot ODF (OpenDocument Format) then it's a good read.
Eve quotes a bit of advice from Gartner about XML:
Users: Recognize that you eventually will be saving your office product data in an XML-based format. Users that need ODF support today or need to comply with ISO standards should explore applications that support ODF. These applications may be cheaper to acquire, and enable different functionality, but the migration will not be inexpensive and will involve compatibility issues when exchanging documents with Microsoft Office users. If you need compatibility with Microsoft Office formats or cannot cost justify a migration, lobby Microsoft to support ODF and look for plug-ins that allow you to open and save ODF files from within Microsoft applications.
Vendors supporting any application using document formats that deliver content to people: Seek opportunities to leverage ODF, particularly "mash-up" approaches to content creation and sharing.
Well this is nice advice to users as far as the ODF bit goes, but misses the big point that always seems to get missed when people talk about word processing formats. I think Rita Knox and Michael Silver of Gartner Research should have added these two little words: “use styles”. I add them to all my posts about word processing, just about.
And as for the advice to vendors, “mash-up” approaches are great, but the mash is not going to be too tasty if you try to work with any-old ODF document. See the post I wrote about Writely, and my recent concerns about how Word might map to ODF. The list-formatting model in the OpenDocument spec, and the interactions between ad-hoc lists, paragraph styles, ad-hoc paragraphs and list styles across different applications is too horrible to think about. Not to mention the fact that lists in ODF have multiple levels, which are very hard to control via OpenOffice.org at least.
The solution is to use templates like the ones available from the ICE project(home page is a bit out of date, but there will be a new one soon, with lots more doco, along with a beta of the official 1.0 release). There we are able to “Mash” together word and OpenOffice.org software quite successfully 'cos we teach people to use styles.