This paper has described a system for presenting variable-length on-line documentation, which allows the user to select the degree of verbosity of the text presented. The results so far on a small-scale have shown that reasonable-quality texts can be produced dynamically. The cost of document markup stops this approach being used on texts of short display-life, but makes it economical for documents of longer duration where length-variability has value.
Apart from text-length, Variable-Length documents allow the user a small degree of content-control, to the degree that they can determine the relevance of each RST relation (or of elements of a schema).
The major problem for the system involves restoring coherence after text-pruning, particularly in areas of reference, discourse markers, paragraphing and punctuation. The problems of paragraphing and punctuation have been solved, and solutions are suggested for the other two areas.
Another problem occurs when material important to the text is not included in nuclear positions in the RST-tree: nuclearity does not guarantee importance to discourse goals (although there is a strong correlation between nuclearity and importance). This is why, in the long term, approaches such as Rino&Scott (1996), which take intentional structure as well into account show some promise. While information about intention structure is not easy to mark up, it would be available in a system doing full text generation from intentions.
Regardless of the problems of this approach, the system is up and running on-line. New documents are being added as time allows, to test the generalisability of the approach.
Future development will include features such as allowing the user to zoom in on text by clicking on it. I will soon make sentence punctuation hyper-clickable, which would result in the pruned text under that sentence being provided.
The notion of variable length on-line documents has great value to information providers and information readers alike -- imagine if this document had been provided variable-length, you could have read the two page version instead!