f the substation equipment. At the 2019 event, there were 13 companies that provided IEC 61850-9-3/IEEE C37.238-compatible equipment, and 13 companies also provided compatible applications or IEDs. 7.5.1 IEEE C37.238-2011 and 2017 Power Profile The Power Profile is defined in IEEE C37.238-2017, "IEEE Standard Profile for Use of IEEE 1588 Precision Time Protocol in Power System Applications," which is a revision to the previous C37.238-2011 standard (Annex B of C37.238-2017 outlines the differences between the 2011 and 2017 versions). The profile version number has been bumped from 1.0 to 2.0. C37.238 specifies a profile that extends the capabilities of the PUP (IEC 61850-9-3:2016) profile to define the use of PTP for power system protection, control, automation, and data communication applications utilizing a packet transport. An example of an extension is the introduction of a new TLV in the Announce message to track grandmaster and network time inaccuracy. Another extension in the 2011 version over 61850-9-3 was the requirement of PTP messages to be sent with the (CoS) priority value of 4, SO they must include an 802.1Q VLAN tag with a default VLAN ID of 0. This VLAN tag was known to cause interoperability issues between the 2011 edi- tion and 61850-9-3. Subsequently, C37.238-2011 was divided into a base profile specified in the PUP (IEC 61850-9-3) profile and the 2017 version that concentrates on the extended capabilities beyond the PUP profile. The goal of this change was to increase interoperability between different implementations. This is the same reason that many options and values available in IEEE 1588-2008 have been set to fixed values in these profiles. As with the two preceding profiles, the message interval for Announce, Sync, and Pdelay_Req is fixed at 1 per second. Not only variations in the message rates but some other mechanisms are specifically disallowed with this profile. They include the E2E path delay mechanism, unicast transmission, and negotiation. The devices in the transport network ne