Thomas A. Phelps

Robust intra-document locations

Abstract Several types of existing and next-generation hypertext functionality, including external hyperlinks, annotations, and transclusions, rely on references to locations within another resource. If the document domain cannot guarantee referential integrity, but rather is more like the World Wide Web, in which documents change regularly and without notification, potentially invalidating internal location references, it is crucial to build robustness into the intra-document location resolution mechanism, so that locations continue to function even as documents change chaotically. This paper aims to begin a process to evolve a standard for (normative) robust location descriptors and (non-normative) reattachment algorithms. We discuss criteria for evaluating the robustness of an intra-document location mechanism. Then we describe robust locations , an approach we believe meets these criteria. Robust locations include a standard minimal location descriptor and a recommended reattachment algorithm. We also suggest what can be done when the changes are so great that location resolution is problematic. Finally, we describe the implementation of robust locations within the Multivalent Document system.

Toward active, extensible, networked documents: multivalent architecture and applications

Rich varieties of online digital documents are possible, documents which do not merely imitate the capabilities of other media. A true digital document provides an interface to potentially complex content. Since this content is infinitely varied and specialized, we must provide means to interact with it in arbitrarily specialized ways. Furthermore, since relevant content may be found in distinct documents, we must draw from multiple sources, yet provide a coherent presentation to the user Finally, it is essential to be able to conveniently author new content, dejine new means of manipulation, and seamlessly mesh both with existing materials. Wepresent a new general paradigm that regards documents with complex content as “multivalent documents”, comprising multiple “layers” of distinct but intimately related content. Small, dynamically-loaded program objects, or “behaviors”, activate the content and work in concert with each other and layers of content to support arbitrarily specialized document types. Behaviors bind together the disparate pieces of a multivalent document to present the user with a single untjied conceptual document. As implemented in Java in the context of the World Wide Web, multivalent documents in effect create a customizable virtual Web, drawing together diverse content and functionality into coherent documentbased inte~aces to content. Examples of the diverse jimctionality in multivalent documents include: “OCR select and paste”, where the user describes a geometric region on the scanned image of a printed page and the corresponding text characters are copied out; video subtitling, which aligns a video clip with the script and language translations so that, e.g., the playing video can be presented simultaneously in multiple languages, and the video can be searrhed with text-based techniques; geographic information system (GIS) visualizations that compose several types of data from multiple datasets; and distributed user annotations that augment and may transform the Content of other documents. In general, a document management infrastructure built around a multivalent perspective can provide an extensible, networked system that supports incremental addition of content, incremental addition of interaction with the user and with other components, reuse of content across behaviors, reuse of behaviors across types of documents, and eficient use of network bandwidth. Multivalent The work reported here was supported in part by National Science Foundation grant IRI-9411334 as part of the NSF/NASA/ARPA Digital