NoteCards is a general hypermedia environment designed to help people work with ideas. Its intended users are authors, designers, and other intellectual laborers engaged in analyzing information, designing artifacts, and generally processing ideas. The system provides these users with a variety of hypermedia-based tools for collecting, representing, managing, interrelating, and communicating ideas. This paper presents the NoteCards system as a foil against which to explore some of the major limitations of the current generation of hypermedia systems. In doing so, this paper highlights seven of the major issues that must be addressed in the next generation of hypermedia systems. These seven issues are: search and query, composite nodes, virtual structures, computational engines, versioning, collaborative work, and tailorability. For each of these issues, the papers describes the limitations inherent in NoteCards and the prospects for doing improving the situation in future systems.

This paper presents an approach for providing hypermedia services in this heterogeneous setting. Central notions of the approach include the following: anchors are established with respect to interactive views of objects, rather than the objects themselves; composable, n-ary links can be established between anchors on different views of objects which may be stored in distinct object bases; viewers may be implemented in different programming languages; and, hypermedia services are provided to multiple, concurrently active, viewers. The paper describes the approach, supporting architecture, and lessons learned. Related work in the areas of supporting heterogeneity and hypermedia data modeling is discussed. The system has been employed in a variety of contexts including research, development, and education

We present a formal definition of the Trellis model of hypertext and describe an authoring and browsing prototype called ffTrellis that is based on the model. The Trellis model not only represents the relationships that tie individual pieces of information together into a document (i.e., the adjacencies) but specifies the browsing semantics to be associated with the hypertext as well (i.e., the manner in which the information is to be visited and presented). The model is based on Petri nets, and is a generalization of existing directed graph based forms of hypertext. The Petri net basis permits more powerful specification of what is to be displayed when a hypertext is browsed and permits application of previously-developed Petri net analysis techniques to verify properties of the hypertext. A number of useful hypertext constructs, easily described in the Trellis model, are presented. These include the synchronization of simultaneous traversals of separate paths through a hypertext, the incorporation of access controls intoahypertext (i.e., specifying nodes that can be proven to be accessible only to certain classes of browsers), and construction of multiple specialized (tailored) versions from a single hypertext.

The areas of application of hypermedia technology, combined with the capabilities that hypermedia provides for manipulating structure, create an environment in which version control is very important. A hypermedia version control framework has been designed to specifically address the version control problem in open hypermedia environments. One of the primary distinctions of the framework is the partitioning of hypermedia version control functionality into intrinsic and application-specific categories. The version control framework has been used as a model for the design of version control services for a hyperbase management system that provides complete version support for both data and structural entities. In addition to serving as a version control model for open hypermedia environments, the framework offers a clarifying and unifying context in which to examine the issues of version control in hypermedia.

This paper introduces the notion of context-aware mobile hypermedia. Contextawareness means to take the users' context such as location, time, objective, community relations etc. into account when browsing, searching, annotating, and linking. Attributes constituting the context of the user may be sensed automatically and/or be provided by the user directly. When being mobile the user may achieve context-aware hypermedia support on a variety of small and medium sized computing platforms such as mobile phones, PDAs, tablet PCs and laptops.

Hypertext is a computer-supported medium for information in which many interlinked documents are displayed with their links on a high-resolution computer screen. The links may be directly activated by a pointing device such as a mouse, which causes the document referenced by the link to appear instantly in a new window on the screen. While the concepts of hypertext are not new, the technology to make it effective is new. This paper reviews most of the existing hypertext systems, and then explores in some detail the fundamental features of hypertext and some of the design options in constructing hypertext systems. The advantages and disadvantages of hypertext are discussed in terms of four major application categories: macro literary systems, problem exploration systems, structured browsing systems, and systems developed to explore hypertext technology.

This paper reflects upon existing composite-based hypertext versioning systems, and presents two high-level design spaces that capture the range of potential choices in system data models for versioning links, and versioning hypertext structure. These two design spaces rest upon a foundation consisting of a containment model, describing choices for containment in hypertext systems, and the design space for persistently recording an object's revision history, with applicability to all versioning systems. Two example points in the structure versioning design space are presented, corresponding to most existing composite-based hypertext versioning systems. Using the presented design spaces allows the data models of existing hypertext versioning systems to be decomposed and compared in a principled way, and provides new system designers significant insight into the design tradeoffs between various link and structure versioning approaches.

: For the past six years, we have been developing a commercial hypermedia system (KMS) based on our previous research with the ZOG system at Carnegie Mellon University. Our experience with ZOG and KMS has convinced us that the data model underlying an interactive system is more important than the user interface in shaping the overall system. In this paper, we show how the KMS data model has influenced important aspects of the user interface. In particular, we show how the properties of KMS frames--their spatial nature, breadth-first view, homogeneity, small size, etc.-- affect the nature of the KMS user interface. Keywords: Conceptual Data Model, User Interface, Hypertext, Hypermedia Introduction We have been developing hypermedia systems for over a decade. This experience has taught us many lessons about the design of interactive software. If there is one central lesson from our experience, it is the fundamental importance of the data model underlying an interactive software system. ...

What is the potential power of hypertext technology? This article examines this question and outlines the answer by focussing attention to a domaim-specific view of hypertext environments. I first define what domain-specific hypertext environments (DSHE) represent. Next, I examine DSHE for the domains of encyclopedic and classical studies, creative writing and interactive fiction, journal and book publishing, insurance policy management, and software engineering. Then I describe in more detail the structure of information to evolve within a DSHE for software engineering in terms of document products, processing tasks and mechanisms, and workplace attributes. In turn, this examination provides the basis for identifying seven dimensions along which the power of DSHE can be defined, experienced, and accumulated. I also address the organizational costs that may be borne to realize this power. I conclude with observations as to the source of DSHE power as well as identifying topics for further investigation. 2

The problems of information overload from the growth of scholarly literature, and the need to use information technology to manage them, were identified by major writers and scientists over fifty years ago. Yet the main form of scholarly communication, the journal, is still circulated in paper form as it has been for over three hundred years. The economic arguments for using computer and communication technology to overcome these problems through a new form of scientific communication, the electronic or digital journal, were vigorously presented in the 1970s. Experimental trials of digital journals with the technologies of the 1970s and 1980s have not been successful. In the 1990s, the continuing value of current journal systems is again being questioned in terms of soaring library costs, the burden of the current refereeing system and the diminishing returns of journal publication brought about by information overload. This paper presents a fundamental examination of the prerequisites...