2. A method of operating a computer system as in claim 1 in which said displaying comprises displaying respective representations showing content of at least some of the documents in the substream.
2. A method of operating a computer system as in claim 1 in which said displaying comprises displaying respective representations showing content of at least some of the documents in the substream. 3. A method of operating a computer system as in claim 2 in which said displaying comprises displaying, as said representations, abbreviated versions of the respective documents.