The Indirect Authoring Paradigm: Obendorf: JoDI

The Indirect Authoring Paradigm – Bringing Hypertext into the Web

Hartmut Obendorf
Applied and Socially Oriented Informatics, Department for Informatics, University of Hamburg
Email: obendorf@informatik.uni-hamburg.de; Web: http://asi-www.informatik.uni-hamburg.de/personen/obendorf/

Abstract

Building hypertext systems to provide the required functionality to write hypertexts has always been a goal of hypertext research. The parallel development of hypertext research prototypes and the World Wide Web has resulted in repeated attempts to replace the Web or offer world-wide all-purpose services to augment the Web with "missing" functionality. The paper argues that focusing on the development of tools that offer support to hypertext authors for specific tasks is a necessary first step for the introduction of sophisticated hypertext features into the Web. Following a brief history of interaction with the Web, we demonstrate why authoring tools for the Web are a critical target for efforts to extend the use of hypertexts in the Web. We introduce indirect authoring as a label for a shared characteristic of different approaches that try to reduce the complexity and cognitive overhead involved in authoring hypertext. Drawing on this analysis, we lay out some consequences for hypertext research. We provide pointers to projects that have started to experinment with indirect authoring, and list immediate research questions. Developing a diversity of task-oriented authoring tools to reduce the cognitive overhead for authoring hypertexts could change the face of the Web.

1 Introduction

This article presents some research issues for the next generation of hypertext systems. Neither a viable alternative nor a serious competitor to the World Wide Web, hypertext research prototypes are nonetheless vitally important for its future development. To inform the development of the Web, it is on the other hand necessary to consider problems and trends surfacing in the Web community when creating new hypertext systems. The first section introduces some discrepancies of the application of hypertext research to the Web.

 
We will try to show in the second section why in the Web we currently see the most problems – and thus the greatest potential for current research – in the area of hypertext authoring. The lack of support for authoring links and the focus on presentation instead of structuring of information is among the reasons for the non-hypertextual nature of the Web.

 
The hypertext community has developed a wealth of systems that allow sophisticated structuring of information. But experience with these systems has also shown that formal ordering of information is a difficult and laborious task for users. In section three, we propose the paradigm of indirect authoring to describe existing and evolving approaches that might allow a larger community of Web users to construct hypertexts, without introducing a large cognitive overhead.

 
Changing the way we read and write cannot be achieved only by developing new systems that try to replace existing work practice in the Web. A much more promising goal, also part of hypertext research since its beginning, is to develop tools that support concrete tasks, thus creating a diversity of specialized authoring tools that augment the existing Web. In the fourth section, we try to identify approaches that support the indirect authoring of hypertexts in specific domains. We also try to collect some research questions that may help us build better hypertext systems.

1.1 Hypertext and the Web

[1] Although the Web is far from being primitive from a user's perspective, its technological basis has often been criticized: The Web has no means to mend broken links, uses only unidirectional and generally untyped links, and cannot externally store more meaningful structures.

The history of hypertext is closely connected to the largest – and in some sense most primitive [1] – hypertext system in existence today, the Web (Cailliau and Ashman 1999). If we want to investigate the future use of hypertext, the Web is a good place to start. Looking at its history we may find reasons for both its overwhelming success and its current lack of sophisticated hypertext features.

 
The Web's success was partly due to NCSA Mosaic and the novelty of its user interface: the combination of text and graphics in a single window (Quittner and Slatalla 1998, Fenn and Maurer 1994). Also, the hypertextual link as a means for integrating different applications was an integral part of Berners-Lee's initial proposal ( Berners-Lee 1989). The ability to point at external addresses, and thus to create a web of information, constituted a critical advantage over the existing Gopher systems ( RFC 1436). The success of the Web has also been attributed to the simplicity of setting up a server and providing content. This simplicity was grounded in the intentionally primitive technological foundation, e.g. the decision to tolerate broken links immensely simplified the (technical) communication needs between Web servers and evaded problems of security and trust.
 

The future of hypertext use is mainly determined by the users of hypertext, who will decide which system might give them most benefit for their tasks. Most users are accustomed to the current Web, and are often quite satisfied with it. Even without trails and sophisticated links, search engines provide fairly reliable access to information. The majority of computer users have made contact with the Web, and client applications for the Web are installed on almost every existing computer. The Web is firmly established – despite repeated predictions, from its early days on, of its not-too-distant decline and replacement through more flexible or more powerful systems (Berghel 1995).
 

Even in a phase when the Web was still taking off, the more structured and hypertext-like approach of the Hyper-G system was competing with the Web without success (Fenn and Maurer 1994). Its presumed benefits over the Web were not enough to persuade users to switch from their recently initiated Web presence to a new infrastructure and a Hyper-G server. While it was difficult to convince users to switch even during that phase, it seems that, today more than ever, no new hypertext system can hope to be a complete replacement for the Web. If a hypertext system can change people's work and recreational activities, it will be the evolving Web.

1.2 A Window to the Web

[2] There is, of course, an increased use of modern technologies in the Web (compare with section 3.1). The point made here is that the time for the adoption of a new technology increases with new versions (e.g. Cascading Style Sheets: CSS1 was almost immediately incorporated in major browsers, CSS2 is not fully supported despite its five years of existence, and CSS3 is taking even longer).

[3] Browsers like Opera, Mozilla and Apple Safari allow new Web pages to be opened in tabbed windows, which means that the same window can be switched between several different buffers containing Web pages. By saving a lot of screen space, this method allows the user to open many different windows at once, and thus directly supports hub-and-spoke navigation.

[4] One important reason for the slow development of browser user interfaces might be that producing browsers is not big business anymore. Microsoft Internet Explorer and Netscape Navigator, although they are regarded as commercial applications, are distributed for free and most users have come to expect these important tools to be available without charge. New companies trying to sell their product, and also open-source projects, will be careful not to completely change the browsing paradigm, as they depend on a steady stream of converts from the major browsers. What makes a browser sell are immediately noticeable features such as nice-looking skins, rendering speed, robustness in displaying Web pages or even standards-compliance, not a history mechanism that will be discovered only during longer use.

The Web's huge success story has created distinctive compatibility problems. Although the technical infrastructure is constantly being developed, the adoption of new technology lags behind [2]. In the mass medium the Web has become, publishers are eager to reach the largest possible audience. New features that are incompatible with commonly used Web Browsers are only sparingly used. Thus, for these Web applications the commonly used subset of HTTP ( Fielding et al. 1999) and HTML (Raggett et al. 1999) limits the communication channel.

 
This is also evident in a lack of innovation in browser interfaces, where the visualization of and interaction with the primary interaction tool, the hyperlink, is almost unchanged from the first Mosaic prototypes ( Weinreich et al. 2001). For reasons of consistency and compatibility, many exciting and interesting research studies on the augmentation of browsing interfaces (e.g. Card et al. 1996, Kaasten and Greenberg 2001, Hightower et al. 1998 and Bouvin et al. 2002) have not been implemented in commercial Web browsers. Some of these studies tried to support structural browsing, similar to the initial Hyper-G Project (Fenn and Maurer 1994), some tried to use a different metaphor from the browser window, e.g. a book that held individual Web pages. A recurrent theme in research is annotation tools for the Web, but again, features from the existing research prototypes, although technically quite stable, have no't become implemented in standard Web browsers.
 

Interestingly, the most noticeable exceptions from this conservative stance surface when the presentation of content is not sufficient. This is true both for (a) more general needs (e.g. for video or sound): these tools can reach a high circulation throughout the user community, and (b) small, well-defined groups with special needs (e.g. musicians looking for sheet music or chemists searching for the documentation of chemical compounds). In these special cases, plug-ins extend the functionality of, but do not replace, the Web browser. Thus, the consistent browsing experience is only temporarily interrupted while the plug-in is in use.
 

In recent years, except perhaps for the invention of tabbed browsing [3], there has been no paradigmatic change in the interaction with Web pages, as browser interfaces have remained consistent and almost entirely unchanged [4].

1.3 New Faces in the Window

[5] The Java programming language might have been an alternative way of accessing distributed data through a common language. As programs written in Java could be executed on almost arbitrary platforms, it was proposed that the browser could be replaced by custom-tailored applications for specific purposes. Among the reasons that this did not come true are lack of interoperability and problems with security, but the most important reason might have been inconsistent interfaces.

[6] There is even the notion of the Web browser replacing standard software packages and becoming the only widely used user interface ( Rees 2002).

[7] The unified "Web look" has even influenced the look-and-feel of current operating systems, where you can choose to switch from the traditional double-click to the Web's single-click style. The blue underlined links have also become a recognizable feature and even influenced the design of advertising campaigns.

The monolithic browser was initially only seen as a step towards special-use applications that would allow more flexible interaction [5]. Custom applications with specifically tailored interfaces would replace the standard browser if additional functionality was be required for a certain task ( Wei 1994). But the browser was neither replaced by task-specific tools nor was new hypertext functionality added. Instead, the logic behind presentational HTML changed to accommodate the need for more flexible applications [6]. This allowed the well-known Web browser to be used for all tasks, unifying the interfaces to a degree that was not possible before [7].

 
In contrast to the slow evolution of Web browser interfaces, the functionality of Web pages has changed downright since the beginnings of the Web. This has happened almost wholly on the server side: dynamically generated content based on user profiles (adaptive hypermedia) or system state is widely used in applications ranging from portals to e-commerce to e-learning. Content management systems work behind almost every news site on the Web, and function-specific tools, such as forums, Weblogs and collaborative hypertexts (e.g. WikiWikiWebs, cf. 3.3), have changed the publishing process in fundamental ways.
 

From handcrafted static HTML (which is still in use today), most users shifted to tools that helped to organize and layout their information. While there is still no consensus on whether to keep coding HTML and CSS by hand or use a graphical tool that might reduce the readability of the underlying source code, the advantages of tools for structuring information are widely acknowledged. Content management tools allow work to be distributed between programmers, graphical artists and content providers. They separate the information from its presentation and from the logic underlying the Web application.

1.4 The Driving Desire to Publish

While the initial Web consisted of only a few servers with a list of personal favorite sites fitting on a "home page", continuous growth and commercialization have changed the face of the Web ( Greenstein 2000). Before business interest in the Web increased to the level we are accustomed to today, however, it was private users who populated the virtual space (Erickson 1996). These individuals created virtual identities on the Web, not only by providing selected information, but also by collecting interesting links and presenting these on their home pages. These links made it possible to provide pointers and simultaneously convey a message about the referrer.
 

A substantial part of the Web is still powered by individuals: apart from the commercial applications that have survived the dot com hysteria into the new millennium, a large part of the Web is strictly non-commercial. This includes government organizations and non-profit organizations, schools and universities and, to a surprisingly large degree, private publications. Indeed, the private desire to produce documents, texts and data for the world to read has probably been one of the driving factors for the success of the Web.

It is not limited to individuals, though.There is also a strong will to publish data in scientific communities. Libraries do not only collect information, but also publish specialized information on the Web (e.g. John 1996). Medical information is published to an increasing extent via the Web ( Curran 2002). At the Hypertext 2003 panel on future visions for hypertext, one of the most popular future visions was the publication on the Web of scientific information, e.g. data from chemical experiments, without being bound by publishers' restrictions concerning copyright and format (Murray-Rust and Rzepa 2004).

1.5 People Do not Read Hypertexts, People Cannot Write Hypertexts

[8] Nelson's original definition of hypertext as non-linear text carries the implication that normal text is linear. As complex arguments in normal text can interweave and refer to one another on several levels, this differentiation is too general (Shneiderman 1989 ).

[9] This is true to different degrees both for literary hypertexts and for mundane Web pages. In closed hypertext systems, as in adventure games, all links are explorable with enough effort. In a system of the scale of the Web this is not true anymore – this is nicely illustrated by numerous copies of the "last page of the internet" on the Web.

Although the Web has often been addressed as a hypertext system, we feel that users of the Web are only rarely confronted with hypertexts. We define hypertext as a text being read using hyperlinks that associatively connect smaller passages of information [8]. Although this is a less demanding definition than that used in the discussion of hypertext rhetoric (Moulthrop 1991), still only a small number of Web pages fit this description ( Miles-Board et al. 2002).
 

Reading hypertexts is an interactive experience – to advance in a hypertext, a reader has to choose between several alternative continuations – and as such often more work than a linear reading. A linear text specifically (and well) designed for a given reading situation will try to answer questions as they come up in the course of its narration. Hypertext repeatedly allows (and forces) the user to choose what will be displayed next for reading, which may be too much for the reader to decide. Adaptive hypermedia has developed in an attempt to reduce the cognitive overhead and the chance of "getting lost", leaving the user fewer but better suited choices. Still, reading hypertexts may leave the reader with more new questions than answers, as an associative hypertext keeps offering more choices as the reader visits more and more nodes: there is no end [9]. Thus, hypertexts will only be read and used if they offer a substantial benefit for a given task. This benefit has been demonstrated (Perlman 1990) for special applications, such as technical manuals (Marchionini and Shneiderman 1988, Yankelovich et al. 1985), and also to some extent for literary hypertexts (Gee 2001), but for day-to-day use the need for hypertexts seems to be less obvious (for a discussion of possible advantages of hypertext reading see Rouet 1992).

 
Even more importantly, writing (literary) hypertexts is hard, so hard that very few people choose it as a profession. Most people will not change their way of writing easily to accommodate the use of hyperlinks: consciously writing hypertexts is too much of a change from their current practice ( Charney 1994). Vannevar Bush's writings (Bush 1945) have often been interpreted in the sense that writing hypertext is like making associations and thus a natural task; but hypertext is not "like the brain" (McKendree et al. 1995). In many applications, the utility of hypertext has to be demonstrated first.

 
It is also an unproven claim that hypertext technology will have an effect on our cognitive capacity, often made in analogy with the evolution from oral to literate cultures; and there is also no consensus on whether a possible effect will be beneficial (Nadin 1997). It is doubtful that we will develop general, natural abilities for writing hypertext in the near future. Writing hypertexts is and will remain a difficult task. Thus, the question of appropriate tools comes into focus.

2 Hypertext Authoring

[10] Playful in the beginning (e.g. the large variety of color bullets that came immediately into use), using the full possibilities of the new medium (3D fonts, animations), the design of Web pages has generally changed into something more subtle and better to read.

[11] For an example of what can be done with CSS, see http://www.csszengarden.com/ or http://www.w3.org/Style/CSS/.

In the early days of the Web, a simple-to-setup server, a text editor and some pictures were all that was needed to create one's own hypertext. This simplicity ?, together with a compelling new user interface (a collage of graphics and text in a single window!) (Quittner and Slatalla 1998), probably accounts for the immediate and overwhelming success of the Web. While the design focus of HTML had been the structuring of data (Berners-Lee et al. 1999, Cailliau and Gillies 2000), it soon became obvious that the user's preference was that of creating the desired look and feel of their documents [10]. On the other hand, commercial applications called for the interoperability of data.
 

Technological developments of recent years have dealt with these concerns. CSS ( Bos et al. 1998) allows sophisticated styling of Web pages [11], XML ( Bray et al. 2000) is employed as a universal tool for information exchange. On the downside, authoring for the Web is not that simple anymore: the new powers come at a price. The complexity could be reduced with appropriate support, but the commonly employed tools do not offer much help.
 

In this section we will try to clarify why this is an opportunity for hypertext research, instead of searching for a new killer application that could replace the Web as we know it today. Enabling larger communities of users to create hypertexts seems a much more concrete and promising task for the future.

2.1 Shortcomings of Actual Tools

An informal survey of 35 publicly available and widely used HTML editors conducted in spring 2003, including both WYSIWYG and source code editors, free and commercially sold software, indicated that linking support in these applications can only be considered very poor ( Obendorf 2003b). While some of the low-level editors listed all available attributes for anchors, they provided no help in finding meaningful values for these. The high-level site management tools were not much better: although it would be possible to sift through the Web site automatically for structural and textual data to provide help in filling the metadata gaps ( Weinreich and Lamersdorf 2000), the support for link creation was at best limited to finding target documents.

 
The results of these shortcomings are immediately visible when looking at the use of attributes in HTML Web pages: in another informal study ( DuCharme 2002), almost no metadata were found to be present, link types and even link titles were not used (use in link tags: <0.1% for types, <0.4% for titles, respectively). In a further study looking for associative links on the Web (Miles-Board et al. 2002), the authors found less than 0.075% (!) of their random sample of Web pages to match their criteria for associative linking.

2.2 Structuring versus Authoring

Authoring has always been a driving force behind the idea of hypertext. The hypertext visionaries Vannevar Bush, Douglas Engelbart and Theodor Nelson, all saw the structuring of information as one, perhaps the most important, application of hypertext.

 
Bush advocated specialist-created trails of information (Bush 1945). His prototypical user was a scholar, creating a historical account of medieval England. Thus, he focuses on creating a trail through existing information, although he occasionally "inserts a comment of his own" or writes an analysis that he then stores in the memex device. Engelbart's main focus was the creation and manipulation of information organized in easily accessible hierarchical structures ( Engelbart 1962). His prototypical user was a "knowledge worker". Extending Bush's vision, Engelbart's user built an argument that, on top of its hierarchical structure, allowed links to nodes and substructures. The system supported different views on the data, but the hierarchy served as the basic element. Nelson (1987), in contrast, stressed the freedom of authors to represent the interdependence of concepts, thus creating complex interlinked structures.
 

The notion of structure has been an important landmark in hypertext discussion ever since. This discourse has often been led from the reader's point of view. Authoring for everyday users, however, often has the function of creating documents that, simply stated, can be read and printed by others. The focus of attention is on published content; the publication form is also an important factor. This is evident in the (mis)use of HTML tags to layout documents instead of structuring them. The question of structure is often of secondary importance to these users.
 

Structure may in fact be an obstacle for authors. Although missing structure, as might be observed in the Web, may mean that a reader has greater problems finding the desired information, demanding the provision of structure may discourage potential authors. While the process of accessing information is quite fragile and users may quickly turn to another information source if they cannot find what they are looking for, the process of authoring is even more vulnerable: if the cognitive overhead introduced by structuring draws attention away from the task at hand, the products of writing will differ strongly.
 

Thus, for systems aiming at producing hypertexts, discrete support of the authoring process, and reducing breakdowns, is critical. Widespread use of hypertext as a communications media, as called for by Bernstein (1999), cannot be answered only by developing more powerful hypertext systems that allow the sophisticated structuring of information. Instead, writing hypertexts must be made easier.

2.3 Simplifying the Creation of Hypertexts

In a technical sense, authoring for the Web is becoming more and more complex due to the new technologies that become gradually more widely used. This is to different degrees equally true for Web design (CSS), structuring information (XLink, HTML 4.0 predefined semantic types) and the implementation of advanced hypertext features (through a dynamic, server-side implementation or the use of a public service).
 

[12] There are tools that specifically support the authoring of private home pages. However, their functionality is often so limited that no more than the equivalent of a business card can be produced without employing more powerful tools.

Today, available tools are often general-purpose applications. Whether the task is to create a private home page [12], an online magazine, or an e-commerce site, the tool should provide support to all kinds of authoring projects. On the other hand, we found that the current tools lack appropriate support even for linking documents, let alone typing or providing metadata. We believe it is necessary to pay close attention to the particular task that can be supported by adding functionality. The design goal should be that of producing minimally complex tools with just the required functionality; the tool used to create hypertexts on the Web should relate directly to the user's activity (Bodker 1991).

3 The Promise of Indirect Authoring of Hypertexts

It has been a repeated finding in hypertext research that authoring hypertext, and especially authoring relations and structure, is a very difficult task (Nanard and Nanard 1993, Shipman and Marshall 1999). The cognitive overload created by structuring, and the misunderstandings that can arise when typing systems are used, prevent many authors from creating hypertexts. On the other hand, there is also a general consensus that hypertexts are desirable ( Bernstein 1999). Rather than proposing a novel, general solution for authoring hypertext on the Web, we would like to promote a new approach to supporting the authoring of hypertext. Instead of explicitly supporting structural features of hypertext, thus placing the focus on system functionality, we would like to name some approaches that focus on the use of hypertext by users.
 

[13] A quote from the Hypertext 2003 discussion was "Hypertext is what is in the mind (between the user and the interface)". This holds true only for readers of a hypertext. A writer can well produce a hypertext without having the interlinking connections in her mind before starting to write. So the hypertext evolves with and through writing, even if the author does not consciously focus on the interdependencies.

An obvious solution is to make the authoring easy by distracting the user from the fact that she is authoring a hypertext [13], a complex interlinked network of nodes. To enable the user to master the complex task of building a hypertext, she must not be required to map the entire hypertext space in advance. As the main idea is that links are built through work processes, this could be called implicit linking. Good examples of approaches building on this idea are the generic link ( Carr et al. 1995) and spatial hypertexts (Marshall and Shipman 1995).

 
As an example for existing and emerging hypertexts, three established and three emerging approaches to authoring hypertexts are presented here in more detail.

3.1 The Generic Link

In its early days, with its very limited number of possible sites, the Web could be made accessible by "home pages", link lists that mentioned interesting resources for a particular topic. Today's Web could not be imagined without search engines. One use for search engines is to make up for non-existing associative links, finding information that is only textually mentioned in Web pages. Thus, this first approach to hypertext authoring is not to create hypertext at all.
 

[14] These include Mozilla and its derivatives, Opera, the Apple Safari browser and also Microsoft Internet Explorer with the Google toolbar installed.

An increasing number of browsers [14] allow the selection of specific words in a Web page and, through a context menu, the automatic initiation of a query. This feature closely matches the simplest form of a generic link ( Hall et al. 1992): thus, this well-known feature of hypertext systems has entered the Web without attracting much attention. In contrast, an earlier attempt to introduce the generic link feature – this time controlled only by a single company, Microsoft – unleashed a storm of protest throughout the user community ( Hughes and Carr 2002, Kaminsky 2001). It should also be noted that an important feature of the generic link is missing from the Web: permanent external storage. Although search engines can find useful information, they will not find all available information, and the result set will vary at different times.

3.2 Associative Hypertext by Keywords: WikiWikiWebs

[15] The first Wiki (http://c2.com/ppr) played an important role for the people behind the pattern movement in software technology.

[16] Some of the nodes in a WikiWikiWeb are often adopted by individual authors, who carefully look after "their" nodes and function as both experts and editors for their favorite topics.

The success story of WikiWikiWebs started with a group of people who were very much interested in developing their ideas into a common theory and structuring a complex topic [15] (Leuf and Cunningham 2001). This was supported by using a novel and innovative form of authoring in these systems. First, everyone could edit everything; the idea of collaboration was present in a pure and unrestricted form. Second, and of more consequence to this discussion, a web of links was created by the introduction of a concept called WikiNames: the spelling decided whether something was a keyword and linked the keyword to its definition. As with the generic link, a hyperlink was automatically created every time a concept was mentioned in the text. Furthermore, a definition node was created and later filled with information for each WikiName, which encouraged the creation of an "organically grown" hypertext [16].

 
Together, these two simple, yet powerful concepts allow even authors who are completely unaware of the notion of hypertext to create a complex network of ideas, definitions and discussions.

3.3 Collage: Spatial Hypertexts

Forcing users to create a formal representation along with their texts can prevent the use of hypertext systems (Shipman and Marshall 1999), or lead to "misuse" of pre-defined type systems (Nanard and Nanard 1993). The class of spatial hypertext systems was developed as a consequence. In spatial hypertext, e.g. VKB ( Shipman et al. 2001) and Tinderbox (Bernstein 2003), everything is implicit. A spatial hypertext is shaped by creating small notes and positioning these in a two-dimensional space. Often, attributes can be assigned to these notes, and notes can be put inside others. There is no defined meaning for relative spatial positions, color or even hierarchical inclusion.

 
Nonetheless, these systems are useful for authors who can develop their own system of codes and relations while writing (or leave it to intuition and later define the level of formalization). It is also possible to extract very simple structures automatically from spatial hypertext and publish the resulting hypertext on the Web ( Shipman et al. 1995). Although the preservation of context can be realized with hyperlinks or even transpointing windows ( Nelson 1995), it is also possible to transfer some spatial characteristics into the result rendered on the Web. Simple co-representation on the same Web page can also create hypertexts (Bernstein 2003) as the spatial and graphical layout conveys structure in a strong sense (Tufte 1990).

3.4 Composition, Transclusion and Annotation

Hypertext can be created by manipulation of text. When this happens in a process where information is both consumed (read) and produced, the newly produced information is still closely related to the information sources used. Preserving these relations in semantic types will produce a hypertext where the history of ideas and arguments is explicitly represented ( Uren et al. 2003). The source texts are part of the composition of the resulting hypertext.

 
Closely related are approaches where only the links to the original documents are preserved during the collection of material. (Nelson 1987) coined the term "transclusion" for this technique. Hunter Gatherer ( schraefel and Zhu 2001) is an example of a simple tool implementing the transclusion approach: by collecting "components" from the Web, a "collection" can be created and later edited.

 
Annotations are another approach employed working with material available on the Web. Most people naturally create annotations as they read. There have been successful efforts to support paper-based reading techniques on digital devices ( Schilit et al. 1998), but still there is no annotation tool in use in the context of the Web. Annotations differ from composition and transclusion in their private nature ( Marshall and Brush 2002). If personal annotations are to be incorporated into a form of digital library ( Marshall 1997), it is important to put equal value supporting a natural reading process and on the extraction of useful information ( Obendorf 2003). Directly connected to both user tasks and resources in the Web, annotations could form the basis for authoring hypertexts.

3.5 An indirect authoring paradigm

Although the approaches mentioned in the preceding paragraphs differ in many respects, they have a common characteristic: authoring takes place in the context of a concrete task. While the text is directly authored, the hypertext, consisting of (typed) links or enriching the text with other forms of attributes, is created indirectly. Depending on the type of interaction of the author with the system, hypertextual functionality is created for a prospective reader. Indirect authoring can take forms ranging from those that need no special action of the author (generic links) to those that require nonformal representations (spatial hypertext) or trivial conventions (WikiWikiWebs) to process models describing and supporting a specific authoring process (incremental formalization of personal annotations or spatial hypertexts).

 
Indirect authoring can be taken as a starting point for thinking about new hypertext applications. Users will seldom create hypertexts for the sake of creating hypertexts but they might want to use hypertext created for their specific needs. It is thus necessary to enable users to create hypertexts without interrupting their normal work. A system that provides only minimal features but offers these without high cost will have a better chance of being used than a sophisticated system that needs the user to devote much time and effort to be able to use it.

4 Some Consequences for Future Hypertext Research

[17] Web Services allow access to a distributed service provided via standard Web protocols (using HTTP and XML) for arbitrary clients. They can therefore be understood as another take against the unifying Web browser and towards special-use applications. In consequence, the semantic Web might open opportunities for custom tools to access data published on the Web. These tools might augment Web browsers and, for special applications (e.g. reading newsfeed), even replace them. On a smaller scale, this is already reality, as Web Services offer the same services normally encapsulated in Web interfaces via a defined interface that can be used by custom Web clients (e.g. Web search via Google).

This article has argued that while Web clients and link interfaces have changed only marginally since the "birth" of the Web, applications available on the server side are changing rapidly, as is the content accessible through the Web. New tasks served through the Web demonstrate the need for custom features. Due to the huge success of the Web and its dependence on a unified interface (cf. section 1.3), no single system can hope to replace the Web in the near future.

 
Even the semantic Web, which is often seen as the Next Big Thing, is subject to the competition of today's Web. This is visible in the efforts undertaken to create portals powered by semantic Web techniques, but usable with a standard Web browser (e.g. Quan et al. 2003), and the recent emphasis on Web Services by the World Wide Web Consortium [17] as the first step towards a Semantic Web (e.g. Berners-Lee 2003). This denys even the existence of a new killer application as initially suggested (Berners-Lee et al. 2001) and instead advocates the integration of existing applications via the semantic Web.

 
Thus, it seems that in the immediate future, the Web browser will be the window through which hypertext on the Web is accessible, thus limiting the user's options for interactivity. Still, only a fragment of the interactivity possible in Web browsers is put into use by today's Web pages, which cannot generally be considered hypertextual in nature (cf. section 1.5).

4.1 Developing a Diversity of Specialized Authoring Tools

Even today, a number of specialized tools for writing hypertext employing different modes of editing are in use. Consequently, there will be no single killer application for everyone, but rather evolving generations of tools for content creation. New forms of hypertext on the Web call for new tools, and for each task the optimal mode of support for indirect authoring will differ. Systems that are successfully finding their niche in the ecosystem of the Web, such as the aforementioned Weblogs and WikiWikiWebs, demonstrate that limiting the cognitive overhead for authors to a minimum enables users to create individually useful hypertexts in the Web.

 
A promising approach to developing applications for authoring hypertext is by prototyping specialized applications for well-defined user groups. Developing for well-defined stakeholders and generalizing the results for a larger audience has long been a successful practice in application development (Cooper 1999, Mayhew 1999). There is a growing number of systems that follow this approach: (Miles-Board, Carr et al. 2003) developed a tool for managers writing reports; as they review and revise reports, their activity is recorded and used to create descriptive metadata. Miles-Board, Deveril et al. (2003) created a hypertext tool supporting the writing of dance critique, paying special attention to the linear nature of dance performances. Gronbaek et al. (2003) created a system that allowed architects to associate data with real-world objects, such as samples of building materials, and Uren et al. (2003) try to support the arguments employed in scholarly critique. In many of these projects indirect authoring and a variant of the linking-by-interacting approach has been implemented successfully.

 
Indirect authoring can also be applied to other existing hypertext paradigms. For example, the work of Shipman et al. (1995) and  Shipman and McCall (1999) on spatial hypertext and incremental formalization shows how spatial organization that is intuitively created by an author can be transferred into more formal representations, thereby creating a hypertext. Publication tools could transform informal representations into hypertexts suitable for publication. They could utilize the user's experience with copy-and-paste or drag-and-drop techniques, introducing direct manipulation techniques to the authoring of hypertext (compare with section 2.1).

4.2 Some Open Questions for Indirect Authoring Tools

[18] There has been some work on cognitive models underlying the writing process (Smith et al. 1987) and the role of external representation (Neuwirth and Kaufer 1989). The former defines a model where a text is produced from a network of thoughts via a hierarchy (as a table of contents) to the linear narrative, which is then consumed by the reader to again build a hierarchy and a network of thoughts. The latter focuses on the production of summaries and states that hypertext systems should be more flexible and support more than one hierarchy. There is, however, no empirical evidence for these models, and in some respect they contradict findings from cognitive psychology ( Charney 1994).

Careful investigations of authoring processes are needed [18] to determine which hypertext features will be useful in certain situations and how the creation of structure can be supported by custom tools. Open issues include questions such as:

  • Which level of support can you provide with your system?

  • How flexible must it be?

It is also still unresolved why certain hypertext features are immediately incorporated into commercial software while others only surface repeatedly in research prototypes.

 
An important characteristic of many hypertext systems is a higher degree of interactivity than possible with standard Web pages; the user cannot only passively consume information but actively contribute to it (even if only by personal annotation). Under the label of the "Writable Web" this has been a focal point of hypertext research. But while the Web as a whole still lacks the means to store user-customized information, as was included in the original Web proposal ( Berners-Lee 1989), many server-side applications make good use of user's contributions entered not through a custom interface but through the Web browser.

 
A general shortcoming of existing authoring tools, however, is the closed world in which hyperlinks are authored (much like in historic standalone hypertext systems). Citing or linking across boundaries is not well supported, even though the universal hyperlink has been the main reason for the success of the Web. The boundaries are not only between hypertext systems and static Web pages; pointing to external targets often breaks the internal linking mechanism. For example, the implicit linking mechanism of WikiWikiWebs breaks when external links are included in a Wiki page, even if they point to other WikiWikiWebs. Problems like this should not burden the author. It is necessary to develop standards that allow access to metadata of systems with similar functionality.

5 Conclusion

[19] It is still an open question how to generalize the existing solutions to a larger scope: the linking problem surfaces again when the boundary to the real world is considered. Connecting virtual objects to real meaning has been one of the initial objectives of the semantic Web. Ossenbruggen et al. (2001) show that hypertext research is an important source of experiences and can also inform the development of the semantic Web. A potential semantic Web will face similar problems to those discussed here: "How can authors make use of ontologies?" or "How can they understand and control metadata on their own work?" If authoring hypertexts is still to be possible for users in a metadata-rich environment like the semantic Web, the need for indirect authoring tools is acute.

The authoring of hypertexts is a difficult task for users. This paper shows that current authoring tools for the Web are not very supportive of the construction of hypertexts. The cognitive overhead that is introduced when the user needs to input a formal representation that collides with his immediate task-dependent needs has to be minimized. Indirect authoring describes a shared characteristic of very different approaches experimenting with authoring modes that allow the user to concentrate on meaningful units of information for his immediate task. While the user interacts directly with the text (and possibly a graphical representation), the structure of the hypertext follows from an interplay of user actions and pre-defined conventions.
 

The notion of indirect authoring can be used as a perspective to identify systems, both in the Web and from hypertext research, that are of immediate use to specific user groups. Varying, extending and combining these systems might produce interesting results. Together, a diversity of task-specific authoring tools might provide a larger number of users with the means to produce hypertexts in the Web.

 
The difficulty encountered by authors today when they create metadata for hypertexts points to the risk that adaptive hypermedia and the semantic Web will be initiatives that fit only certain, well-defined communities because of the skills involved [19]. Extending these communities through authoring support tools that minimize the user's overhead will be vital to the success of these technologies.

Acknowledgements

As this article started as a result of informal discussions at Hypertext 2003, thanks go to all who took part in them. The author also thanks the anonymous reviewers for their help in focusing this article. Matthias Finck, Horst Oberquelle and Harald Weinreich provided criticism and helpful comments on an earlier draft. Finally, Bettina von Stockfleth helped to significantly improve the readability of this text. I would also like to thank you, the reader, and invite you to share your thoughts.

References

[Berghel 1995] Berghel, Hal (1995) "The inevitable demise of the Web". ACM SIGAPP Applied Computing Review, Special issue on the Web, 3(2), 5-8

[Berners-Lee 1989] Berners-Lee, Tim (1989) "Information Management: A Proposal". CERN, March (revised May 1990)
http://www.w3.org/History/1989/proposal.html

[Berners-Lee et al. 1999] Berners-Lee, Tim, Mark Fischetti and Michael L. Dertouzos (1999) Weaving the Web: The Original Design and Ultimate Destiny of the World Wide Web by its Inventor (Harper Books)

[Berners-Lee 2003] Berners-Lee, Tim (2003) "Semantic Web Status and Direction". International Semantic Web Conference 2003,  keynote address
http://www.w3.org/2003/Talks/1023-iswc-tbl/

[Berners-Lee et al. 2001] Berners-Lee, Tim, James Hendler and Ora Lassila (2001) "The Semantic Web". Scientific American, May
http://www.sciam.com/article.cfm?articleID=00048144-10D2-1C70-84A9809EC588EF21

[Bernstein 1999] Bernstein, Mark (1999) "Where are the Hypertexts?" 10th ACM Conference on Hypertext, keynote address, Darmstadt, Germany
http://www.eastgate.com/ht99/slides/Welcome.htm

[Bernstein 2003] Bernstein, Mark (2003) "Collage, composites, construction". Proceedings of the ACM Conference on Hypertext, pp. 122-123
http://www.ht03.org/papers/pdfs/18.pdf
http://www.eastgate.com/Tinderbox/

[Bos et al. 1998] Bos, Bert, Hakon Wium Lie, Chris Lilley and Ian Jacobs (1998) "Cascading Style Sheets, level 2, CSS2 Specification". W3C Recommendation, May
http://www.w3.org/TR/REC-CSS2/

[Bouvin et al. 2002] Bouvin, Niels Olof, Polle T. Zellweger, Kaj Gronbaek and Jock D. Mackinlay (2002) " Fluid annotations through open hypermedia: using and extending emerging web standards". Proc. 11th ACM Hypertext conference, Honululu, Hawaii, pp. 160-171

[Bodker 1991] Bodker, Susanne (1991) Through the Interface - a Human Activity Approach to User Interface Design (Hillsdale, NJ: Lawrence Erlbaum Associates)

[Bray et al. 2000] Bray, Tim, Jean Paoli, C.M. Sperberg-McQueen and Eve Maler (editors) (2000) Extensible Markup Language (XML) 1.0 (second edition), 6 October
http://www.w3.org/TR/2000/REC-xml-20001006

[Bush 1945] Bush, Vannevar (1945) "As we may think". The Atlantic Monthly, 176(1): July, 101-108
http://www.theatlantic.com/unbound/flashbks/computer/bushf.htm

[Cailliau and Ashman 1999] Cailliau, Robert, and Helen Ashman (1999) "Hypertext in the Web - a history". ACM Computing Surveys, 31(4), December
http://www.cs.brown.edu/memex/ACM_HypertextTestbed/papers/62.html

[Cailliau and Gillies 2000] Cailliau, Robert, and James Gillies (2000) How the Web was Born: The Story of the World Wide Web (Oxford University Press)

[Card et al. 1996] Card, Stuart K., George G. Robertson and William York (1996) "The WebBook and the Web Forager: an information workspace for the World-Wide Web". In Proc. of SIGCHI 1996, pp. 111-117
http://www2.parc.com/istl/projects/uir/pubs/items/UIR-1996-14-Card-CHI96-WebForager.pdf

[Carr et al. 1995] Carr, Leslie A., David C. De Roure, Wendy Hall and Gary J. Hill (1995) "The Distributed Link Service: A Tool for Publishers, Authors, and Readers". In Proceedings of the Fourth International World Wide Web Conference, Boston, MA, December, pp. 647-656
http://www.w3.org/Conferences/WWW4/Papers/178/

[Charney 1994] Charney, Davida (1994) "The Impact of Hypertext on Processes of Reading and Writing". In Literacy and Computers, edited by Susan Hilligoss and Cynthia Selfe (New York: Modern Language Association), pp. 238-263
http://www.cwrl.utexas.edu/~charney/Charney_hypertext.pdf

[Cooper 1999] Cooper, Alan (1999) The Inmates Are Running the Asylum: Why High Tech Products Drive Us Crazy and How To Restore The Sanity (SAMS)

[Curran 2002] Curran, Charles (2002) "The Medical Journal Meets the Internet. First Monday, 6(7)
http://www.firstmonday.dk/issues/issue7_6/curran/index.html

[DuCharme 2002] DuCharme, Bob (2002) HTML Attributes: What People Use (a semi-scientific study), October 23
http://www.snee.com/xml/a-href.html

[Engelbart 1962] Engelbart, Douglas C. (1962) "Augmenting human intellect: A conceptual framework". Technical report, Stanford Research Institute, SRI, Menlo Park, CA, October 
http://www.bootstrap.org/augdocs/friedewald030402/augmentinghumanintellect/3examples.html

[Erickson 1996] Erickson, Thomas (1996) "World-Wide-Web as Social Hypertext". Communications of the ACM, 39(1), 15-17

[Fenn and Maurer 1994] Fenn, Barry, and Herrmann Maurer (1994) "Harmony...on an expanding net". ACM Interactions, 1(4), 26-37

[Fielding et al. 1999] Fielding, R., J. Gettys, J. Mogul, L. Masinter, P. Leach and T. Berners-Lee (1999) Hypertext Transfer Protocol HTTP/1.1. RFC2616, June
http://www.faqs.org/rfcs/rfc2616.html

[Gee 2001] Gee, Kim (2001) "The Ergonomics of Hypertext Narrative: Usability Testing as a Tool for Evaluation and Redesign". ACM Journal of Computer Documentation, 25(1)

[Greenstein 2000] Greenstein, Shane (2000) "Commercialization of the Internet: The Interaction of Public Policy and Private Choices or Why Introducing the Market Worked so Well". Technical Report, NBER program on "Innovation, Policy and the Economy", Washington, DC
http://www.kellogg.nwu.edu/faculty/greenstein/images/htm/Research/Internet-nberpolicy.pdf

[Gronbaek et al. 2003] Gronbaek, Kaj, Jannie F. Kristensen, Peter Orbaek and Mette Agger Eriksen (2003) "'Physical Hypermedia': Organising Collections of Mixed Physical and Digital Material". Proc. ACM Conference on Hypertext, Nottingham, pp. 10-20
http://www.ht03.org/papers/pdfs/2.pdf

[Hall et al. 1992] Hall, Wendy, Ian Heath, Gary J. Hill, Hugh C. Davis and Robert J. Wilkins (1992) "The Design and Implementation of an Open Hypermedia System". Technical Report CSTR 92-19, University of Southampton
http://eprints.ecs.soton.ac.uk/archive/00000784/

[Hightower et al. 1998] Hightower, Ron R., Laura T. Ring, Jonathan I. Helfman, Benjamin B. Bederson and James D. Hollan (1998) " Graphical Multiscale Web Histories: A Study of PadPrints". Proc. 9th ACM Hypertext conference, Pittsburgh, PA, pp. 58-65

[Hughes and Carr 2002] Hughes, Gareth, Leslie Carr (2002) "Microsoft Smart Tags: Support, ignore or condemn them?" Proc. 13th ACM Hypertext conference, pp.80-81
http://eprints.ecs.soton.ac.uk/archive/00007351/

[John 1996] John, Nancy R. (1996) "Putting Content onto the Internet: The Library's Role as Creator of Electronic Information". First Monday, issue 2
http://www.firstmonday.dk/issues/issue2/content/index.html

[Kaasten and Greenberg 2001] Kaasten, Shaun, and Saul Greenberg (2001) " Integrating Back, History and Bookmarks in Web Browsers". CHI 2001, extended abstract, pp. 379-380

[Kaminsky 2001] Kaminsky, Chris (2001) "Much Ado About Smart Tags". A List Apart Magazine, No. 115, July
http://www.alistapart.com/articles/smarttags/

[Leuf and Cunningham 2001] Leuf, Bo, and Ward Cunningham (2001) The Wiki Way: Collaboration and Sharing on the Web (Addison-Wesley Professional)

[Marchionini and Shneiderman 1988] Marchionini, Gary, and Ben Shneiderman (1998) "Finding Facts and Browsing Knowledge in Hypertext Systems". IEEE Computer, 21(1), 70-80

[Marshall 1997] Marshall, C.C. (1997) "Annotation: from paper books to the digital library". Proc. ACM Digital Libraries Conference, Philadelphia, PA, pp. 131-140
http://www.csdl.tamu.edu/~marshall/dl97.pdf

[Marshall and Brush 2002] Marshall, Catherine C., and A. J. Bernheim Brush (2002) "From personal to shared annotations". ACM CHI'02 conference, extended abstract, pp. 812-813
http://www.cs.washington.edu/homes/ajb/papers/MBCHI02Short.doc

[Marshall and Shipman 1995] Marshall, Catherine C., and Frank Shipman (1995) "Spatial hypertext: designing for change". Communications of the ACM, Vol. 38, No. 8, August, 88-97

[Mayhew 1999] Mayhew, Deborah J. (1999) The Usability Engineering Life Cycle: A Practitioner's Handbook for User Interface Design (Morgan Kaufmann Publishers)

[McKendree et al. 1995] McKendree, Jean, Will Reader and Nick Hammon (1995) "The 'homeopathic fallacy' in learning from hypertext". ACM Interactions, Vol. 3, No. 2, July, 74-82

[Miles-Board et al. 2002] Miles-Board, Timothy, Leslie Carr and Wendy Hall (2002) "Looking for Linking: Associative Links on the Web". 11th ACM Hypertext conference, Maryland, USA, extended abstract, pp. 76-77
http://eprints.ecs.soton.ac.uk/archive/00006977/

[Miles-Board, Carr et al. 2003] Miles-Board, Tim, Leslie Carr, Simon Kampa and Wendy Hall (2003) "Supporting Management Reporting: A Writable Web Case Study". Proc. 12th World Wide Web Conference, Budapest, Hungary, pp. 234-243
http://eprints.ecs.soton.ac.uk/archive/00007327/

[Miles-Board, Deveril et al. 2003] Miles-Board, Tim, Deveril, Janet Lansdale, Leslie Carr and Wendy Hall (2003) "Decentering the Dancing Text: from dance intertext to hypertext". Proc. of ACM Conference on Hypertext, Nottingham, pp. 108-119
http://eprints.ecs.soton.ac.uk/archive/00008137/

[Moulthrop 1991] Moulthrop, Stuart (1991) "Beyond the Electronic Book". Proc. 3rd ACM Hypertext conference, pp. 291-298

[Murray-Rust and Rzepa 2004] Murray-Rust, Peter, and Henry Rzepa (2004) "The Next Big Thing: From Hypermedia to Datuments". Journal of Digital Information, Vol. 5, No. 1, article No. 248
http://hdl.handle.net/2249.2/jodi-136

[Nadin 1997] Nadin, Mihai (1997) The Civilization of Illiteracy (Dresden University Press), see also Project Gutenberg Release #2481, January 2001
http://onlinebooks.library.upenn.edu/webbin/gutbook/lookup?num=2481

[Nanard and Nanard 1993] Nanard, Jocelyne, and Marc Nanard (1993) "Should Anchors be typed too? An experiment with MacWeb". In Proc. ACM Conference on Hypertext, HT'93, Seattle, November

[Nelson 1987] Nelson, Theodor Holm (1987) Computer Lib / Dream Machines (Microsoft Press: Washington)

[Nelson 1995] Nelson, Theodor Holm (1995) "The heart of connection: hypermedia unified by Transclusion". Communications of the ACM, 38:8, August, 31-33

[Neuwirth and Kaufer 1989] Neuwirth, C. M., and D. S. Kaufer (1989) "The Role of External Representations in the writing process: Implications for the Design of Hypertext-based Writing Tools". Proc. ACM Hypertext'89 conference, pp. 319-341

[Obendorf 2003] Obendorf, Hartmut (2003) "Simplifying Annotation Support for Real-World-Settings: a Comparative Study of Active Reading". Proc. ACM Hypertext Conference, Nottingham, pp. 120-121
http://asi-www.informatik.uni-hamburg.de/personen/obendorf/download/2003/p182-obendorf.pdf

[Obendorf 2003b] Obendorf, Hartmut (2003) "An informal study of common web editing tools". Author eprint
http://asi-www.informatik.uni-hamburg.de/personen/obendorf/download/2003/editor-survey.html

[Ossenbruggen et al. 2001] van Ossenbruggen, Jacco, Lynda Hardman and Lloyd Rutledge (2002) "Hypermedia and the Semantic Web: A Research Agenda". Journal of Digital Information, 3(1), article No. 55
http://hdl.handle.net/2249.2/jodi-61

[Perlman 1990] Perlman, Gary (1990) "Evaluating Hypermedia Systems". ACM Conference on Human Factors and Computing Systems, Panel, pp. 387-390

[Quan et al. 2003] Quan, Dennis, David Huynh and David R. Karger (2003) "Haystack: A Platform for Authoring End User Semantic Web Applications". Proc. 2nd International Semantic Web Conference, pp. 738-753
http://haystack.lcs.mit.edu/papers/iswc2003-haystack.pdf

[Quittner and Slatalla 1998] Quittner, Joshua, and Michelle Slatalla (1998) Speeding the Net: The Inside Story of Netscape and How It Challenged Microsoft (Atlantic Monthly Press)

[Raggett et al. 1999] Raggett, Dave, Arnaud Le Hors and Ian Jacobs (1999) HTML 4.01 Specification, W3C Recommendation, 24 December
http://www.w3.org/TR/html4/

[Rees 2002] Rees, Michael J. (2002) "Evolving the browser towards a standard user interface architecture". ACS Conferences in Research and Practice in Information Technology (CRPIT) series, Volume 7 - User Interfaces 2002, edited by John Grundy and Paul Calder (Australian Computer Society Inc.), pp. 1-7
http://crpit.com/confpapers/CRPITV7Rees.pdf

[RFC 1436] Anklesaria, F., M. McCahill, P. Lindner, D. Johnson, D. Torrey and B. Alberti (1993) RFC 1436 - The Internet Gopher Protocol (a distributed document search and retrieval protocol), March
http://www.faqs.org/rfcs/rfc1436.html

[Rouet 1992] Rouet, Jean-Francois (1992) "Cognitive Processing of Hyperdocuments: When Does Nonlinearity Help?" Proc. ACM European Conference on Hypertext Technology, pp.131-140

[Schilit et al. 1998] Schilit, B.N., Golovchinsky, G. and Price, M. (1998) "Beyond Paper: Supporting Active Reading with Free Form Digital Ink Annotations". Proceedings of ACM CHI'98, Los Angeles, CA, pp. 249-256
http://seattleweb.intel-research.net/people/schilit/sch98a.pdf

[schraefel and Zhu 2001] schraefel, m.c. and Zhu, Yuxiang (2001) "Interaction Design for Web-Based, Within-Page Collection Making". Proceedings of the 12th ACM Conference on Hypertext and Hypermedia, pp. 125-126
http://shaka.dgp.toronto.edu/hg/papers/schraefel_zhu_ht01short.pdf

[Shipman and McCall 1999] Shipman, Frank M. and R. McCall (1999) "Supporting Incremental Formalization with the Hyper-Object Substrate". ACM Transactions on Information Systems, 17, 2, April, 199-227
http://www.csdl.tamu.edu/~shipman/tois-hos.pdf

[Shipman et al. 1995] Shipman, Frank M., Catherine C. Marshall and Thomas P. Moran (1995) "Finding and Using Implicit Structure in Human-Organized Spatial Layouts of Information". Proc. ACM CHI'95, pp. 346-353
http://www.acm.org/sigchi/chi95/Electronic/documnts/papers/fms_bdy.htm

[Shipman and Marshall 1999] Shipman, Frank M., and Catherine C. Marshall (1999) "Formality Considered Harmful: Experiences, Emerging Themes, and Directions on the Use of Formal Representations in Interactive Systems". Computer Supported Cooperative Work, Vol. 8, No. 4, October, 333-352
http://www.csdl.tamu.edu/~shipman/formality-paper/harmful.html

[Shipman et al. 2001] Shipman, Frank, H. Hsieh, R. Airhart, P. Maloor and J. M. Moore (2001) "The Visual Knowledge Builder: A Second Generation Spatial Hypertext". Proc. ACM Conference on Hypertext, pp. 113-122
http://www.csdl.tamu.edu/~shipman/vkb/vkb-ht2001.pdf

[Shneiderman 1989] Shneiderman, Ben (1989) "Reflections on Authoring, Editing, and Managing Hypertext". The Society of Text: Hypertext, Hypermedia and the Social Construction of Information (MIT Press) pp. 115-131
http://www.cs.umd.edu/Library/TRs/CS-TR-2160/CS-TR-2160.ps.zip

[Smith et al. 1987] Smith, John B., Stephen F. Weiss and Gordon J. Ferguson (1987) "A Hypertext Writing Environment and its Cognitive Basis". First ACM Hypertext Conference, panel, pp. 195-214

[Tufte 1990] Tufte, Edward R. (1990) Envisioning Information (Graphics Press)

[Uren et al. 2003] Uren, Victoria, Simon Buckingham Shum, Gangmin Li, John Domingue and Enrico Motta (2003) "Scholarly Publishing and Argument in Hyperspace". In Proc. 12th World Wide Web Conference, Budapest, Hungary, pp. 244-250
http://www2003.org/cdrom/papers/refereed/p137/p137-uren.html

[Wei 1994] Wei, Pei Y. (1994) "A Brief Overview of the VIOLA Engine, and its Applications". Author eprint, August 16
http://www.xcf.berkeley.edu/~wei/viola/violaIntro.html
The Viola Home Page http://www.xcf.berkeley.edu/~wei/viola/violaHome.html

[Weinreich and Lamersdorf 2000] Weinreich, Harald, and Winfried Lamersdorf (2000) "Concepts for improved visualization of Web link attributes". Computer Networks, Selected Papers from the WWW9 Conference, 33(1-6), 403-416
http://vsys-www.informatik.uni-hamburg.de/papers/hyperscout-www9.pdf

[Weinreich et al. 2001] Weinreich, Harald, Hartmut Obendorf and Winfried Lamersdorf (2001) "The Look of the Link: Concepts for the User Interface of Extended Hyperlinks". Proc. 12th ACM Conference on Hypertext, pp. 19-28
http://asi-www.informatik.uni-hamburg.de/personen/obendorf/download/2001/lookoflink.pdf

[Yankelovich et al. 1985] Yankelovich, Nicole, Norman Meyrowitz and Andries van Dam (1985) "Reading and Writing the Electronic Book". IEEE Computer, 18(10), 15-30