om the IEEE (TSN was formerly known as Audio Video Bridging [AVB]). In 2020, the TSN Task Group of IEEE 802.1 published an approved revision to the original 2011 standard. PTP Industry Profile (PIP) from the International Electrotechnical Commission (IEC) for Layer 2 Peer-to-Peer (L2P2P) and Layer 3 End-to-End (L3E2E) transport. The IEC 62439-3 (2016) standard outlines the two profiles in Annex C. It also contains Annexes A and B that outline how to use Parallel Redundancy Protocol (PRP) and High-availability Seamless Redundancy (HSR) to create doubly attached (redundant) PTP clocks. IEC 61850-9-3 (2016) Power Utility Automation Profile (PUP). This profile was adapted from the L2P2P profile from IEC 62439-3 (2016) Annex C and included in this joint IEC/IEEE standard. The use of doubly attached clocks is optional in this profile. IEEE C37.238-2017. Known as the "Power Profile," this profile takes the preceding PUP and extends it to define the use of PTP in the power system, electrical substations, and across the distribution grid. SMPTE ST-2059-2 and AES67 Media Profiles. This pair of profiles from two different industry organizations (the Society of Motion Picture and Television Engineers and the Audio Engineer- ing Society) support the dissemination of audio and video content in a professional and broad- cast setting. PTP Enterprise Profile, RFC draft-ietf-tictoc-ptp-enterprise-profile-18 (might be a later draft version depending on when you are reading this). This Enterprise Profile is intended to work in large enterprise networks, for example, in financial corporations, where the time accuracy needed is tighter than available from NTP. White Rabbit (WR). This is an extension to PTP that was developed to synchronize nodes in a packet-based network with sub-nanosecond accuracy. It makes use of PTP 1588-2008 combined with SyncE and a link setup and calibration method to address link asymmetry (that requires specialized hardware). 7.5.1 IEEE 802.1AS-2020: Timing and Synchronization for Time-Sensit- ive Application