DuCharme announces at once that this book is not for beginners. To benefit from its content, readers need substantial experience with Standard Generalized Markup Language (SGML), which was established by the International Standards Organization in 1986. It has become a popular standard in technical document preparation because it facilitates the transfer of text from one application to another. Those who specialize in the field contend that SGML should do for text and documents what SQL has done for databases.

This is a hands-on instruction book on designing, authoring, composing, and publishing. Books of this type are often useful if they combine the characteristics of a reference manual, a tutorial, and a user’s guide. The author contends that this work is three-fourths a user’s guide and one-fourth a tutorial. I have found it to be a useful reference manual as well; it includes a quick reference on Emacs and PSGML keystrokes.

The book goes a long way toward increasing the acceptance of SGML as the international standard for the electronic interchange of documents and data. The author notes that SGML is an evolving standard, and that by the time the book goes to press, the standard will have changed. He suggests that the best resources for update materials are newsgroups and Web pages. He also contends that the proliferation of free software gives us a clue to the technology’s progress.

SGML views documents as being composed of three types of information: data, such as text, graphics, video, and sound; structure, which is the relationship between data elements, such as headings and subheadings, paragraphs, and lists; and format (or style), which is the appearance of the document. SGML provides the rules for defining the structure and tagging the data in documents. A Document Type Definition (DTD) can be formulated for any type of document according to these rules. Once the data and structure of documents are defined, a program (parser) can read a DTD, process the document accordingly, and deliver the document in a format required by the user.

Thus, as an open system, SGML allows for the easy exchange of documents from one format to another. SGML can describe documents independent of any hardware or software. An important derivative of SGML is the Hypertext Markup Language (HTML), which is used for the various documents made available through the World Wide Web.

This book also focuses on the Document Style Semantics and Specifications Language (DSSSL), which does two things with SGML data. It is a transformation language, which specifies ways to take an SGML document and change the order of its elements, delete elements, and generate new context; it is also a style language, which lets you specify how a document should look. Thus, DSSSL is a standard language for writing processors of SGML (to turn it into something) and translators (to convert one DTD to another). Jade, which the book uses, is a package that currently implements the first function and will eventually implement the second.

Another focus of the book is on finding and diagnosing problems in the document conversion process, such as tagging and attribute problems. DuCharme devotes a chapter to interesting publicly available SGML documents on which one can exercise SGML knowledge. According to the listing, much of the world’s great literature is available free in SGML format.

This book has a lot to teach beginners about this growing, evolving field. I recommend it highly to those interested in document interchange.