I believe that this enables/disables the ability for the FileManager to follow links to subdirectories of the site libraries. It does not affect which libraries you can see from the Library browser.
You may or may not want to allow individual instructors direct access to the library's file structure. If you do allow access you will usually want to make sure that the permissions set on the library does not allow it to be modified by the web server.
Installation
Can't start apache after cvs upgrade
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