Shareable object references can be aware of versioning in following ways:
1. Always use latest version of referenced object 2. Always stay at current version 3. Notify author of referenced object updates
In all of these cases, changes to referenced object do _not_ constitute changes to referenceing object.
There are few ways to notify referrer about change of referenced object. When reference is made, referer choses what he wants.
* Each change - an email * Digest - user gets summary of changes in all objects once in a while
Special page which provides filtered summary of changes, i.e. for all objects referenced by given course.