This is a per-machine system policy that can be used when the administrator only wants per-machine applications installed.
If this policy is not set, the installer searches the registry for applications in the following order: managed applications registered as per-user, unmanaged applications registered as per-user, and finally applications registered as per-machine.
If this policy is set to 1, the installer ignores all applications registered as per-user and only searches for applications registered as per-machine. Calls to the Windows Installer application programming interface or system ignore per-user applications. An attempt to perform an installation in the per-user installation context causes the installer to display an error message and stops the installation. In this case, the Windows Installer also prevents per-user installations from a terminal server.