Attaching PDF files

A number of companies are making available with a download a PDF version of the booklet that comes with the physical cd. Deutsche Grammophon does this for almost all downloads, for example. It would be very useful to be able to access this downloaded PDF directly from OCD, perhaps with a link in the Notes section in much the same way a url can be included in the web links for an artist. (Maybe this can already be done, but I haven't figured out how to do it.)

And, while I am on this subject, I would also like to be able to include multiple web links that are specific to a CD and not to an artist, so that I could include links to online reviews.