It has long been recognized that in order to build a good system in which a person and a machine cooperate to perform a task it is important to take into account some significant characteristics of people. These characteristics are used to build some kind of a "user model". Traditionally, the model that is built is a model of a canonical (or typical) user. But often individual users vary so much that a model of a canonical user is insufficient. Instead, models of individual users are necessary. This article presents some examples of situations in which individual user models are important. It also presents some techniques that make the construction and use of such models possible. These techniques all reflect a desire to place most of the burden of constructing the models on the system, rather than on the user. This leads to the development of models that are collections of good guesses about the user. Thus some kind of probabilistic reasoning is necessary. And as the models are being used to guide the underlying system, they must also be monitored and updated as suggested by the interactions between the user and the system. The performance of one system that uses some of these techniques is discussed. 1.

Document preparation systems that are oriented to an author's preparation of printed material must permit the flexible specification, modification, and reuse of the contents of the document. Interactive document preparation systems commonly have incorporated simple representations--an unconstrained linear list of document objects in the 'What You See Is What You Get' (WYSIWYG) systems. Recent research projects have been directed at the interactive manipulation of richer tree-oriented representations in which object relationships are constrained through grammatical specification. The advantage of such representations is the increased flexibility that they provide in the reusability of the document and its components and the more powerful user command that they permit.

Software development environments can increase user productivity by presenting information in more useful ways. This paper describes Proteus, the presentation system of Ensemble, a software development environment that supports a wide variety of language and document capabilities. Proteus provides a set of services which allow the appearance of software development documents, such as programs or design specifications, to be determined by formal specifications of style. Proteus is based on a generic model of presentation services and is intended for use with a wide variety of media. 1 Introduction One of the key purposes of a software development environment should be to allow users to view the artifacts of the development process in a variety of insightful ways. Insight may be stimulated by one or more thoughtful presentations of a program's text. Alternatively, the results of program analyses may be the source of new insight. Whether these results need to be presented in textual or g...

Although XML Document Type Definitions provide a mechanism for specifying, in machine-readable form, the syntax of an XML markup language, there is no comparable mechanism for specifying the semantics of an XML vocabulary. That is, there is no way to characterize the meaning of XML markup so that the facts and relationships represented by the occurrence of XML constructs can be explicitly, comprehensively, and mechanically identified. This has serious practical and theoretical consequences. On the positive side, XML constructs can be assigned arbitrary semantics and used in application areas not foreseen by the original designers. On the less positive side, both content developers and application engineers must rely upon prose documentation, or, worse, conjectures about the intention of the markup language designer --- a process that is time-consuming, error-prone, incomplete, and unverifiable, even when the language designer properly documents the language. In addition, the lack of a substantial body of research in markup semantics means that digital document processing is undertheorized as an engineering application area. Although there are some related projects underway (XML Schema, RDF, the Semantic Web) which provide relevant results, none of these projects directly and comprehensively address the core problems of XML markup semantics. This paper (i) summarizes the history of the concept of markup meaning, (ii) characterizes the specific problems that motivate the need for a formal semantics for XML and (iii) describes an ongoing research project --- the BECHAMEL Markup Semantics Project --- that is attempting to develop such a semantics.

Various algorithms have been proposed for the difficult problem of producing aesthetically pleasing drawings of trees, see [15, 17] but implementations only exist as "special purpose software", designed for special environments. Therefore, many users resort to the drawing facilities available on most personal computers, but the figures obtained in this way still look "hand-drawn"; their quality is inferior to the quality of the surrounding text that can be realized by today's high quality text processing systems. In this paper we present an entirely new solution that integrates a tree drawing algorithm into one of the best text processing systems available. More precisely, we present a T E X macro package TreeT E X that produces a drawing of a tree from a purely logical description. Our approach has three advantages. First, labels for nodes can be handled in a reasonable way. On the one hand, the tree drawing algorithm can compute the widths of the labels and take them into account for...

Authoring is the collection, selection, preparation and presentation of information to one or more readers by an author. The thesis takes a new, critical look at traditional approaches to authoring, by asking what knowledge is required and at which stages of the process. From this perspective, traditional authoring is seen to entrench an early commitment to both form and content. Although the late binding of form is now commonplace in structured document preparation systems, a similar delay in the binding of content is necessary to achieve user-tailored interaction. The authoring paradigm we have developed to service this goal is called intent-based authoring, because the author supplies at compile-time a communicative goal, or intent. Just as SGML editors and HTML browsers defer rendering decisions until run-time by referring to a local style-sheet, intent-based authoring systems defer content-selection decisions until run-time when they refer to models of both author and reader(s). T...

The Web Consortium's XML Linking working group is developing specifications to enable more advanced hypertext functionality on the Web: in particular fine-grained anchors, external annotation, and bidirectional links. This paper examines basic goals and approaches; describes HTML linking limitations XML Linking seeks to overcome; and surveys the Working Group's primary specifications: XPath, XPointer, and XLink. As of this writing, the last two, while well advanced, are not final recommendations, and so are subject to change. Consult the W3C Web site for the latest versions. Background The HTML tag set and its hypertext element types such as A are very useful and popular, yet have difficulties apparent at larger scale and for more diverse data. These include practical matters such as divergence of implementations and mixing of formatting with structure (I, TT, HR versus H1, OL, BODY); but also more fundamental limitations: . Element types only of certain kinds, which do not model novel kinds of information (say, PRICE for a mail-order catalog).

Index preparation is a tedious and time-consuming task. This paper indicates how the indexing process can be automated in a way that is largely independent of a specific typesetting system and independent of the format being used. Fundamental issues related to this process are identified and analyzed. Specifically, we develop a framework for placing index commands in the document. In addition, the design of a general purpose index processor that transforms a raw index into an alphabetized version is described. The resulting system has proved very useful and effective in producing indexes for several books, technical reports, and manuals. A comparison of our system with indexing facilities available from a variety of other document preparation environments is given.

flo is a language for including flowcharts into documents typeset using the UNIX™ ditroff. A basic flowchart can be created with minimal effort by inputting only the basic algorithm written in a Pascal-like notation. The example below illustrates the general capability of flo. The flowchart to the left is obtained from the input to the right.

... This paper discusses ways in which such numbering can be described and proposes a simple paradigm for declarative specification of how components should be numbered. The class of algorithms for incremental update of component numbers is studied and the "best" such algorithm is developed in detail.