Searching around the forum, seems like this has been kicked around for a few years now.
Given that tasks (well, that's what they are: tasks!) disappear after two years and that they are not a good place to keep reference material anyway, we need some way to link the tasks (in a project, say) to the reference material for that project.
(FWIW: Palm had this, many years ago; if my memory is correct (not a given!), all that was needed was a / and the letter L (for Link). Simple. Elegant. Effective. Can we get the same???)