Sync- lock, also called phase- lock, emulates the old control track or pilot tone method of synchronization. The system reads the timecodetime codes, synchronizes the transports, and takes any deliberate offsets into account. Once the system is locked, the slaves only use the speed information that is derived from the timecodetime code. Specific timecodetime code addresses are ignored. This method allows the tape machines to stay locked even if the timecodetime code relationships change. See chase-lock.