With XHTML you have the mixed benefits of being able to parse the structure as an XML document (scanning for heads and subheads for example) while still being able to read it in a Web browser. XML as a Document Management Format. I want to make a distinction here between document formats and document management formats. Document management formats are very closely allied to the other current rages in computing circle these days’ directories. While the conventional example of a directory is something like a phone book, I personally have had more than my share of problems with this description. In computer circles a directory is essentially a hierarchical structure that can be queried to retrieve information about a computer system the file structure on a network drive, user information and so forth.

If the mention of the word hierarchical is ringing some bells here then you’re beginning to get a feel for working with XML. In theory you could represent a directory system through the use of an XML document. The Lightweight Directory Access Protocol (LDAP) architecture that is currently deployed in numerous servers is built around the older X.500 protocol as a way of using a directory-like notation of retrieve information about a system. Servers that convert LDAP result into XML (or that accept XML X path syntax for retrieving LDAP information) are likely to become commonplace by the time this book is published as the two formats are not dissimilar. Similarly XML can be used to create one or more topic maps into a document space. A topic map can be thought of as a hierarchical table of contents for a whole Web Site. The advantage of a topic map is what it can arrange document by their content rather than their location in a directory.

While the structure here is regular (making it more of a data-centric XML document) its primary purpose is to create a relational map to documents (or conceivably to sub documents depending on the documents and the server) in what amounts to a concept space. In its simplest form such a space would probably be expressed as a tree-view of some sort but more importantly it is way of abstracting relationship without trying them into an explicit file directory structure. It also reduces redundancy them into an explicit file directory structure. It also reduces redundancy of documents since you do not need such a document in more than one place to show a relationship. Topic maps and XML-enabled directories will change the way that we look at document management and will ultimately even change the way we think about documents themselves. Since more than one topic map can be assigned to a document space topic map essentially enable the capability of shifting your perspective about the information you have available to you. As we move in caressingly into a data-rich environment (even, perhaps into one where data is considered pollution) XML’s role in document management will become critical. XML as a Data Format. A funny thing happened on the road to XML adoption as the next HTML: several people simultaneously discovered that a table is a data structure. For example consider a simple table of line items from a purchase order.