We introduce the idea of combined documents, show how they can be used for mixed-media publication and discuss some of the technical issues involved. Background Electronic, multi-media publishing is becoming established as an alternative to conventional publishing on paper. They allow non-linear progression through the text. Sound and moving images can be added. Sections can be copied into new documents.
Electronic bookmarks are less convenient than bits of paper.
Adding personal notes to electronic documents is difficult. Our solution is to publish material as an ordinary, printed document that can be read in the normal way, enjoying the usual benefits of readability, accessibility and portability. However, when observed by a camera connected to a computer, the material acquires the properties of an electronic document, blurring the distinction between the two modes of operation. Our initial experiments have applied this technology to computer-assisted learning. The two parts can now be united.