Why Structured Documents?
Likely beneficiaries of the structured document approach sometimes resist it due to the certain costs (and stress) of the change in technologies and practices it requires. New tools, staff re-training, and the time penalty involved in managing the changeover, are all valid cost and risk issues. The benefits must therefore outweigh these issues. So, what are the benefits?
When using an XML-sensitive word-processor, the XML DTD (Document Type Definition) acts as a sophisticated templating mechanism that forces authors to work within pre-defined document structure constraints. It is simply not possible, for example, for an author to insert a document title anywhere but at the beginning of the document, and it is also not possible for the author to forget to give the document a title. The benefit of this is either improved document collection consistency, or reduced costs in ensuring such consistency.
Another effect of authoring within a document template is that the author is not concerned with the format of the content when it is finally published, so wastes no time on learning or applying the fiddly formatting techniques that general-purpose word-processors and DTP applications provide.
Instant Re-Formatting and Boilerplate Updating
Formatting of the documents is applied by processing tools and stylesheets after the content has been produced and approved. This publish process can be re-run at any time, and changes to document formats can be incorporated into the process. It is not necessary to re-open all of the documents in a collection and re-format them individually.
Similarly a change to boilerplate text, such as updating a copyright notice, is performed by modifying a transformation stylesheet - not by editing many individual documents.
Multiple Media Publishing
The first and most significant reason for adopting a structured document approach is the increasing need for multiple media publishing. The ability to format and re-format content for different media in a fully automated way significantly reduced costs. The same content can be delivered to paper (print production), to the Web and to CD-ROM products. The content can be sliced, diced and re-formatted to make the most of each media.
When the content of structured documents is sufficiently complex, it may be possible to re-use parts of the documents to create sub-products. This can achieved using fully automated processes and, of course, the resulting sub-products can then be published to multiple media as described above.
Systems that are built to work with XML documents are interchangeable, and should be built using interchangeable components. If a product is no longer deemed to be suitable for the purpose, or is no longer supported by its vendor, it is a relatively simply matter to swap-in an alternative product. The content itself does not need to be migrated to the demands of the new product.
Note that any vendor who insists that all of the components of their editorial and publishing system are mutually dependent should be treated with suspicion - this is a ploy to "lock in" clients, and therefore to subvert the vendor independence benefit of XML.