The user is able to retrieve information through query specification, browsing through documents, and browsing within documents. Queries can also specify presentation information such as position on the page. The authors mention presentation modes such as browsing, zooming, transparencies, narration, voice segments, annotations, and process simulation. Transparencies allow annotations to be overlaid on images. Narration is different from voice segments because it begins automatically when a certain point in the document is reached, while specific action must be taken to hear voice segments.
Process simulation is scripted animation by fast page turning.
But the system seems to suffer from creeping featurism. This paper gives no clear answers to these fundamental questions. The Digital Library is published by the Association for Computing Machinery.