Although my view of the mountains driving home is now obscured, I know the mountains are still there. Once I'm home, I can look out my back windows and enjoy an impressive mountainscape. As with the mountains, established data hasn't disappeared. Moving data to the Web, however, can block access, the online equivalent of a viewshed. New online interfaces both obscure data and provide new views.
Media can enhance or impede our view of data.
Price policies affect the concealment and revelation of content. In her overview of Italian information resources in this issue, Valerie Matarese mentions the inability of a company database interface to search by economic activity. The information is there, you just can't select on it. This deficiency is far from new. Traditional print periodical indexes have far too few access points.