You can use Group Policy to modify the file types that Windows 2000 excludes for offline access according to the local computer, an organizational unit (OU), or the domain. For example, you can exclude files from an inhouse database application that uses file extensions that don't exist in the default exclusion list. To edit the local policy, run gpedit.msc to open the Microsoft Management Console (MMC) Group Policy console. To edit the policy for an OU or for the domain, open the MMC Active Directory Users and Computers snap-in. Open the Properties dialog box for the OU or domain object, then go to the Group Policy tab. Select the Default Domain Policy, then click Edit to open the Group Policy console.
In the console's left-hand pane, expand Computer Configuration\Administrative Templates\Network, then select the Offline Files object. In the right-hand pane, double-click Files not cached. Select the Enabled option, then enter the extensions you want to make unavailable. Use the format *.ext (where .ext is the appropriate file extension). Click OK. Note that modifying a policy in this way doesn't simply add an extension to the list of unavailable extensions, but instead replaces the default settings. Therefore, you must manually enter all the file extensions you want to exclude from offline access, including all the default file types. The new policies are in effect the next time the target computers start.