A phasor data concentrator (PDC) is defined in this standard as a set of functions that may be performed on synchrophasor data. It describes the PMU measurement network and indicates the place of the PDC in it. The standard defines the minimum functions that a PDC should perform. The performance requirements for these functions are given, and the ways they can be tested are described. Cybersecurity is discussed, and while its importance is acknowledged in the overall system, it is beyond the scope of this standard, which is viewed as specific to PDC functions.