File Replication service
Abbreviated as FRS, File Replication service is a multithreaded, multiple-master replication engine in Microsoft Windows NT versions 3.x and 4.0. Windows 2000-based domain controllers and servers use FRS to replicate system policies and logon scripts for Windows 2000-based and earlier clients. The File Replication service replaces the LAN Manager Replication (LMREPL) service.
See also "How To Use File Replication Service File and Folder Filters in Windows 2000" from Microsoft Help and Support.