Equipment that provides a timing signal whose long-term accuracy is maintained at 1 x 10-11 or better with verification to Coordinated Universal Time (UTC,) and whose timing signal may be used as the basis of reference for the control of other clocks within a network. The primary reference source may generate a timing signal completely autonomous of other references, in which case cesium beam technology is suitable. Alternatively, the primary reference source may not be a completely autonomous implementation, in which case it may employ direct control from normal UTC-derived frequency and time services. Not to be confused with primary time standard, primary frequency standard.