Block read access via the File System API on these sites

If you set this policy, you can list the URL patterns that specify which sites can't ask users to grant them read access to files or directories in the host operating system's file system via the File System API. If you don't set this policy, 'DefaultFileSystemReadGuardSetting' (Control use of the File System API for reading) applies for all sites, if set. If not, users' personal settings apply. URL patterns can't conflict with 'FileSystemReadAskForUrls' (Allow read access via the File System API on these sites). Neither policy takes precedence if a URL matches with both. For detailed information about valid url patterns, see https://go.microsoft.com/fwlink/?linkid=2095322. * isn't an accepted value for this policy. Example value: https://www.example.com [*.]example.edu