The nature of a medium shapes it. That's what makes hypertext interesting. That's why we're here in Darmstadt, at a hypertext conference.
But the nature of the medium isn't the only factor.
The channel lies between the Manufacturer and the Audience. It may include wholesalers, retailers, salespeople, publicists, gatekeepers, impresarios, promoters and pundits.
The channel, too, shapes the work.