In 4D v6.7, the "System folder" command now accepts an optional parameter. This allows you to specify the type of system folder for which you would like to obtain a pathname. However, to use this new capability on the Windows platform, the system file "SHFolder.DLL" version 4.71 minimum is required to be present in the active Windows system folder. Otherwise, the command will return empty strings for any folder type you specify in the parameter other than 0 (System).
For details on this new feature, see the 4D v6.7 Upgrade manual page 77-78, or the 4D Language Reference manual: