For Builders of SGML DTDs

Abstract

Those who build SGML DTDs are often called “document analysts” or “designers”, because they decide on the constraints of what document structures are allowed in some given situation. Obviously the kinds of elements they choose vary enormously (POEM versus PARTS-LIST, for example), but the same basic structures recur in many DTDs. Two especially common issues of the many that come up are:

• • When the order of content in the document must differ from the “conceptual” order. The most common case is footnotes and floatable figures, whose conceptual position may be hard to pin down. Hypertext links (the links themselves, not their endpoints or anchors) and other structures also reveal this issue. In some cases, there is no single sensible order.

• • When to use containers. Documents that have only titles and no containers for large structured objects like chapters, dictionary entries, and bibliography entries are generally agreed to show bad structural design. But there are gray cases, such as lists of term/definition pairs, where experts vary widely on whether the pairs ought to be grouped.