There’s one final detail of the physical and logical structures of
DocBook that we’ve left out: where can your document begin? In other
words, what are the valid “document elements” of DocBook
documents? Naturally, you can start at
book, but can you also start at
chapter? What about
If you come to DocBook from the DTD days, this question may seem odd. A DTD doesn’t provide any facility to impose constraints on where a document can begin. If the element occurs in the DTD, you can start with it.
RELAX NG does give us the ability to impose such constraints. In fact, it requires that we do. Of course, we could make the constraint vacuous by listing every possible element as a potential document element.
But, on reflection, that’s not necessarily the best choice. It’s
valuable to have metadata associated with documents, so only elements with
info element can be root elements, but not every
element with an
info element is currently included. In
DocBook V5.0 the following elements are available:
With the next point release of DocBook, V5.1, the
technical committee may take the position that any element that can
info wrapper can be a document element. This would ...