Thanks but I don't think I answered my question.....or maybe the question that I waited to ask until the end of my message wasn't clear enough. For files that are not 'Moodle-bound' an external repository is fine but if we want to encourage teachers to work on collaborative development of curriculum (e.g. write quizzes, lessons, etc.) that are 'Moodle-bound' an external repository won't work.
I guess I should have asked a question in my first post to make clear what it is that I would like to be able to do. I want to allow teachers to create activities within Moodle and be able to upload files etc. but not delete said activities and files. Is it possible to create a user role (permissions) that allows for this type of a setup? (it's obvious to me now that this is not possible)
I don't think that "If you can upload a file, you ought to be able to delete it -- or to overwrite it with a newer version" is necessarily axiomatic here. The forums are a good example of the process that I would like to be able to implement course wide - upload something or create it within Moodle and then have 30 minutes to edit it after which you can view the item but cannot edit or delete it. I do however, understand the downsides to what I have suggested. One being that if users cannot delete (or even edit) content that they uploaded/created, the said course could quickly become an unorganized mess.
Having not received any input/feedback on my post, I came up with a solution that is a more realistic alternative given the limitations I now understand. I've created a 'collaboration course' that will be used as a 'contribution' area into which teachers can upload files and create activities and from which these activities, files, etc. will be imported into courses that they are deemed appropriate for (we're calling them 'resource courses'). These resource courses will then be maintained such that only a select few admins can tamper with them but will be visible and accessible (via import) to all teachers (enrolled in them as non-editing teachers) so they can peruse them and then import activities etc. into the courses they are teaching.
I'll just have to make sure the 'collaboration course' is checked on a very regular basis so that new items can be saved and imported into the 'resource courses' where there will be no danger of them being accidentally deleted.
Any comments on what I am trying to do with Moodle are welcome.
Jason