Abstract: "In this introductory 'Commentary and Opinion' essay, the "editors of the journal describe why they and publisher decided to start the journal, and what they hope to accomplish."

'Markup Languages: Theory & Practice is a peer-reviewed technical journal publishing papers on research, development, and practical applications of text markup for computer processing, management, manipulation, and/or display. The scope of the journal includes: 1) design and refinement of systems for text markup and document processing; 2) specific text markup languages; 3) theory of markup design and use; 4) applications of text markup; 5) languages for the manipulation of marked up text.'

"The scope of the journal is wide enough to include current and future markup applications but is designed to limit the subject scope sufficiently to make the journal coherent. As may be seen, the journal is not limited to SGML and XML and their applications, though we believe them to be markup languages of considerable interest. SGML was not the first, and XML is unlikely to be the last, language of their kind; we hope this journal will prove a useful forum for discussions of design and implementation issues relating to markup languages present, past, and future. We hope Markup Languages: Theory & Practice will be equally hospitable to articles on theory and articles on practice. In the field of markup languages, theoretical questions may have immediate and obvious practical implications, and practical problems often raise profound and important theoretical issues. The best theorists continually learn from practical experience; the best implementers realize that there is 'nothing so practical as a good theory'."

"Markup Languages: Theory & Practice will include material of a variety of categories, including: 1) articles: especially on theoretical and practical aspects of markup or markup usage; 2) announcements: describing events or activities, especially future events likely to be of interest to our readers; 3) commentary and opinion: essays, such as this one, consisting primarily of the authors' opinions; 4) practice notes: discussions of common practice, suggestions for improved standard practice, or comparisons of methods for achieving similar goals; 5) project reports: descriptions of a project or application reviews: discussion and description of books, software, web sites, etc. that may take the form of essays, short narrative reviews, or annotated tables of contents; 6) squibs: short (from one to a few pages) statements of fact, descriptions of problems, or anecdotes; 7) standards reports: discussions of any of the ever growing set of standards relating to markup."

Abstract: "The earliest computer-aided hypertext systems were built in the 1960s, and (unlike some of the most popular later systems) fully integrated it with their hypertext functionality. Brown University's FRESS was the first hypertext system to run on commercial hardware and OS. It actually handled complex documents better than non-hypertext systems, and so was used as a publishing system as well as a collaborative hypertext environment for teaching, research, and development. FRESS had considerable support for document structuring and markup, affording separation of structure from formatting and hypertext semantics. It also provided a variety of coordinated views and a very powerful conditional-structure and view-specification mechanisms that suited it for many tasks still considered hard today: dynamic document assembly, structured information retrieval, and on-the-fly customization of even very large documents for the user, display device, and context. This paper gives an overview of FRESS's design approach especially with regard to its treatment of markup and structure; it discusses some ways that document structures differ from other familiar information structures; and argues that a sophisticated model of document structure is necessary to realize fully the potential of hypertext."

Abstract: "Exceptions are used in many standard DTDs, including HTML, because they add expressive power for DTD authors. However, there is a tradeoff: although they are useful, exceptions add significantly to the complexity of DTDs. Authoring DTDs is a difficult task, and existing tools are of limited use because of the lack of a suitable formal model for exceptions. This paper describes methods for constructing a static model that completely and precisely describes DTDs with exceptions. A software tool has been written to implement the methods and to demonstrate some practical applications. Examples are shown of how the tool is used for DTD authoring, and some useful extensions of the tool are described. For one example DTD, the output of the tool is converted into a regular expression grammar. Preliminary studies indicate that general case algorithms can be developed for this conversion. This would allow existing theory for the context free languages to be used in developing SGML applications. Statistical results are shown from running the software tool on a number of industry and government DTDs and for three successive versions of HTML. The results illustrate that the complexity of DTDs in practice is approaching, or has exceeded, manageable limits with existing tools. The formal model and its applications are needed for SGML and continued development of these methods may impact the evolution of HTML, XML, and related web publishing standards. Some specific projects are proposed, where continued development of the model can result in more powerful tools and new kinds of applications for SGML."

[Conclusion: The paper provides evidence to illustrate] "the complexity of DTDs with exceptions, which in turn implies high costs for DTD design and corresponding problems with quality. These results also show that the complexity of some DTDs is approaching (or has exceeded) manageable limits given existing tools for designing and understanding them. There is clearly a need for more powerful tools for DTD design and analysis and for subsequent SGML processing. The software tool described in this paper is useful for understanding (viewing) DTDs with exceptions and for detecting errors caused by the incorrect use of exceptions. Several practical extensions of the tool are described that provide other new capabilities for DTD analysis. Because exceptions are an integral part of SGML, any generalized SGML tool must support them. There are previous theoretical results for formal language models of DTDs with exceptions ([Matzen, "Model"]; [Kilpeläinen and Wood, "SGML and Exceptions"]). However, this is the first description of an implementation, and thus it provides a foundation for a new generation of applications and tools."

"The expanded DTDs output by the software tool are a powerful extension of the model; these can be used to construct DTDs without exceptions that are pseudo-equivalent to the original DTDs with exceptions. This allows authors to design DTDs using the expressive power of exceptions while managing their side-effects. Also, the methods shown for converting DTDs with exceptions to regular expression grammars provide a powerful formal foundation, the existing theory for the context free languages, to be used in developing new kinds of SGML applications. The continued development of the methods and tools described in this paper can be a significant factor in the future success of SGML, and they would affect the evolution of HTML, XML, and other standards for the World Wide Web."

Abstract: "Quality control in electronic publications should be one of the major concerns of everyone who is managing a big project, like a digital library. Collecting information from several different sources raises problems of quality assurance. With SGML we can solve part of the problem, structural/syntactic correctness. There are situations where pre-conditions over the information being introduced should be enforced in order to prevent the user from introducing erroneous data; we shall call this process data semantics validation. In this paper we present ways of associating a constraint language with the SGML model. We present the steps towards the implementation of that language. In the end, we present a new SGML authoring and processing model which has an extra validation task: semantic validation. We also describe some cases in which quality could be improved with this new working scheme."

[Conclusion:] "Our main concern in the work reported in this article was the improvement of quality control in SGML-based electronic processing. In this context we discussed a new SGML authoring and processing model to remedy the lack of semantic validation in the traditional SGML model. The main idea was to restrict the values that the user can enter, by associating constraints with the element definitions. This way we can minimize data incorrectness and improve document quality. Through the use of several examples we illustrated the main problems in the implementation of such semantic validation task: data normalization, type inference, and the definition of a constraint language. . ."

Abstract: "The content-reuse system of The Wall Street Journal Interactive Edition makes extensive use of SGML and XML to reorganize and reformat the content presented in the main wsj.com website. This paper discusses how the structures that define an Interactive Journal edition and its component articles are queried, processed, and converted by automatically triggered content-processors, allowing us to quickly fill requests by potential publishing partners to feature our branded content in their contexts."

[Conclusion:] '. . . All of our content-reuse processes owe their flexibility and ease of implementation to our use of SGML and XML. Articles created in SGML have been translated and served out in all sorts of flavors of HTML and other plain text formats. Edition structures and configuration files specified in XML are processed and tailored by custom software that allows our editors to specify what constitutes a mini-edition. And when our automatically generated content falls short of serving their audiences completely, an editor can step in and finish the job. . . . Our editors and designers are charged with constantly improving how our news can be accessed, navigated through, presented, and used. And our business-development staff is constantly seeking new ways to raise the visibility of our brand, which often means spreading excerpts from our trove of content out to places and platforms that our primary web site would not otherwise reach. Having our news, and the processes that direct where that news belongs, in an extensible format has proved to be the key to fulfilling their requirements.'

Abstract: "It is unfortunately easy to confuse the terms that SGML uses when discussing characters and character sets. This graphic illustrates the relationships of characters, character sets, and related concepts. [Illustration and definitions for character, character repertoire, code set, character set, code set position, coded representation, character number].

Abstract: "The Document Object Model is a programming interface to HTML and XML documents. The level 1 DOM specification enables application writers to access, navigate, and manipulate the content and structure of HTML and XML documents. The paper describes the motivation behind the work on the DOM, as well as the rationale behind some of the design decisions. A precis of future work is given."

The first nine pages and the conclusion of this book review essay present the case for SGML/XML DTDs - despite the notion of (mere) "well-formedness" in XML. Ensign argues that the temptation to characterize XML as "SGML without the DTD" represents a misunderstanding of the intent in the XML specification.

Abstract: "Extensible Markup Language or XML, a simpler form of SGML, has introduced the concept of a well-formed document, one that doesn't need a DTD. This sounds wonderful - all the benefits of SGML without the expense or restrictions of that darned DTD. But to dismiss DTDs as arbitrary, restrictive constraints on creative freedom is to miss their role as documentation of the truly valuable parts/aspects of your content and as descriptions that enable users to build lights-out processing systems for leveraging that content. Assuming your goal is to make your content more generally useful and to make it valuable across your entire enterprise, you will quickly find that DTDs are not enemies but allies. And once you make that discovery, you'll want these two books in your library: (1) Eve Maler and Jeanne El Andaloussi Developing SGML DTDs: From Text To Model To Markup, and (2) David Megginson, Structuring XML Documents."

The annotated Table of Contents for Developing SGML DTDs complements the corresponding book review article by Chet Ensign, also published in this issue of Markup Languages: Theory & Practice.

The annotated Table of Contents for Megginson's Structuring XML Documents complements the corresponding book review article by Chet Ensign, also published in this issue of Markup Languages: Theory & Practice.