Revision Standard - Active - Draft. A method for real-time exchange of synchronized phasor measurement data between power system equipment is defined. This standard specifies messaging that can be used with any suitable communication protocol for real-time communication between phasor measurement units (PMU), phasor data concentrators (PDC), and other applications. It defines message types, contents, and use. Data types and formats are specified. A typical measurement system is described. Communication options and requirements are described. Cybersecurity is discussed, and while its importance is acknowledged in the overall system, it is beyond the scope of this standard.