1. Apparatus for serving output signals from a serving device to a plurality of browsing devices connected to a network, wherein said output signals represent commands executable by each browsing device so as to display viewable data in accordance with a specified page format, comprising: means for identifying requests from browsing clients that define a request for specified viewable data with commands for displaying said data in a specified format; means for reading data representing said viewable data; means for processing said read data so as to combine a representation of said viewable data with executable instructions; and means for supplying output signals to the requesting browsing device derived from said processed data.