Abstract: Keeping multiple versions of the same electronic artifact is a necessity in many authoring fields, and a serious advantage in all of them. Hypermedia adds to that the issue of relationship management. This poses a few additional problems, especially conceptual ones, but it also provides a reliable and safe solution for the well-known problem of the referential integrity of links. The field of hypermedia has dealt with versioning issues for a long time, since Xanadu considered it a fundamental mechanism for its inner workings. Newer systems, and an important protocol for the WWW, WebDAV, constitute modern approaches to the problem.

Abstract: Researchers in the hypermedia field often lament that the World Wide Web does not support many of hypermedia's rich structuring, navigation and annotation features. What would it take for everyday Web applications to be fully hypermedia compliant, now that the basic hypermedia building blocks exist on the Web? The following four capabilities are the most critical for integrating hypermedia support in the Web environment: edit-capable browsers, storing document content and link anchors separately, external linkbases, and displaying link spans, node and link attributes. Individual developers cannot decide autonomously on how to resolve many of the outstanding issues. Developers need agreed-upon conventions and tools built upon today's Web standards to fully incorporate hypermedia functionality into everyday applications. Categories and Subject Descriptors: H.5.4. [Information interfaces and presentation]

Document representations can rapidly become unwieldy if they try to encapsulate all possible document properties, ranging from abstract structure to detailed rendering and layout. We present a composite document approach wherein an XMLbased document representation is linked via a ‘shadow tree ’ of bi-directional pointers to a PDF representation of the same document. Using a two-window viewer any material selected in the PDF can be related back to the corresponding material in the XML, and vice versa. In this way the treatment of specialist material such as mathematics, music or chemistry (e.g. via ‘read aloud ’ or ‘play aloud’) can be activated via standard tools working within the XML representation, rather than requiring that application-specific structures be embedded in the PDF itself. The problems of textual recognition and tree pattern matching between the two representations are discussed in detail. Comparisons are drawn between our use of a shadow tree of pointers to map between document representations and the use of a code-replacement shadow tree in technologies such as XBL.

ABSTRACT Keywords Documents are often marked up in XML-based tagsets to delineate major structural components such as headings, paragraphs, figure captions and so on, without much regard to documents, after many transformations and ‘typesetting’ processes, often emerge in the popular format of Adobe PDF, either for dissemination or archiving. Until recently PDF has been a totally display-based document representation, relying on the underlying PostScript semantics of PDF. Early versions of PDF had no mechanism for retaining any form of abstract document structure but recent releases have now introduced an internal structure tree to create the so called ‘Tagged PDF’. This paper describes the development of a plugin for Adobe Acrobat which creates a two-window display. In one window is shown an XML document original and in the other its Tagged PDF counterpart is seen, with an internal structure tree that, in some sense, matches the one seen in XML. If a component is highlighted in either window then the corresponding structured item, with any attendant text, is also highlighted in the other window. Important applications of correctly Tagged PDF include making PDF documents reflow intelligently on small screen devices and enabling them to be read out in correct reading order, via speech synthesiser software, for the visually impaired. By tracing structure transformation from source document to destination one can implement the repair of damaged PDF structure or the adaptation of an existing structure tree to an incrementally updated document.

The automated generation of links within a body of educational material is critical to the cost-effective implementation of Technology Based Learning. This paper describes the linking system used by WHURLE- an adaptive web-based integrated learning environment. Structural links are dynamically generated from lessons using an autonavigation system. Authored links are created by teachers or students, and consist of bidirectional links between different points in the content or between WHURLE and elsewhere on the Web. Authored links are defined in a linkbase that is either attached to a lesson (i.e. teacher originated) or to a user profile (i.e. student originated). These links may be single (i.e. one to one), hubs (one to many) or plural (many to many), and are implemented by Goate, a content modifying proxy system.