Both the Guardian and Blogger have featured 'Enetation' , apparently a way to open up weblogs for comment. I have been thinking about what is involved in the 'online collaboration' features of Acrobat. What happens when someone adds to or comments on another person's text? There may be some ideas about critique and learning that help to explain this. So far attempts to encourage people to use PDF for comments have failed. They usually prefer to add text to emails rather than open up a PDF. Maybe this is just familiarity. Maybe PDF is only suitable when a clear record is needed. The signatures are dated. Also it may suit when graphics are involved. The current UK press advertising includes a review process for a design proof. I'm going to try out some enetation now.