The advent of electronic documents and the consequent creation of digital libraries—vast repositories of electronic information—has a profound impact on how we produce, organize, store, retrieve and consume information. All of these activities have been dictated to the present by the technologies used to share information. A change in the underlying technology, namely, the move from paper to electronic documents, offers a unique opportunity to revolutionize how information is archived and disseminated. This paper will focus on a specific aspect of the opportunities opened up by electronic publishing on the NII—the ability to present information in multiple modalities and thereby free it from any single presentation medium.
Traditional printed communication relies on a passive intermediary, paper, for the exchange of information between the author and reader. Ideas put down on paper come back to life only when perused by the reader.
Electronic publishing is mediated by a computer, an agent capable of processing the information. As a consequence, the ideas expressed by an author need no longer be bound to any single “display” form; nor does it require human intervention to translate the information from one displayed form to another. Electronic information can be processed and displayed in a manner best suited to each individual's needs. Thus, the advent of electronic documents makes information available in more than its visual form—electronic information can now be display-independent.
Traditionally, an electronic document has been viewed simply as digitally representing (or the means towards producing) the printed page. Instead, we view the electronic document as the basic entity that represents information; we allow the information to be rendered in different ways—on paper, spoken, processed in different ways by a computer, etc. This change of viewpoint has allowed us to develop ASTER (Audio System For Technical Readings) a computing system that audio formats electronic documents to produce audio documents. ASTER can speak both literary texts and highly technical documents that contain complex mathematics. Moreover, the listener can ask to have parts of a document repeated in different ways: a document has many different spoken views.
The adequacy of the audio rendering depends on how well the electronic document captures the essential internal structure of the information. In this paper, we discuss capturing structure and give guidelines for authors to follow to ensure that their documents exhibit structure adequately.
In the context of the NII, the digital libraries of the future can be viewed as large information servers that allow multiple clients to access and display information in a format chosen by the user. By obviating the need to move physical media, e.g., printed paper or recorded tapes, the NII enables the ready dissemination of multimodal renderings of information.