e of the virtual local-area network (VLAN) tag from IEEE 802.1Q for PTP messages when using G.8275.1. In short, VLAN tags are not allowed, and if a T- GM, T-BC, or T-TSC receives a PTP message with a VLAN tag, the message is dropped. There may be some exceptions when using a T-TC Transparent clock, but a PTP message with a VLAN tag should never appear at a PTP port on any other clock type. There are numerous appendixes and annexes contained in this recommendation that are very helpful to understanding a wide-scale deployment of the technology. Only the main ones are listed here, but it is strongly suggested that you download the document and familiarize yourself with them if you are deploying this profile. G.8275.1 is one of the most active recommendations at the ITU-T, meaning that it receives many contributions from the delegates, SO it is updated rather regularly. There was a revision in March 2020 that includes several amendments and an amendment consented at the October 2020 plenary. Link to recommendation: https://handle.itu.int/11.1002/1000/14543 G.8275.2: Precision Time Protocol Telecom Profile for Phase/Time Synchron- ization with Partial Timing Support from the Network The ITU-T G.8275.2 profile is another of the important profiles for those operators transitioning to 5G, most especially in North America. It covers the layer 3 (unicast) version of PTP for those net- works that cannot fully support PTP at every hop from the master to the slave. From the scope of the recommendation: The profile specifies the IEEE 1588 functions that are necessary to ensure network element interoperability for the delivery of accurate phase/time (and frequency) synchronization. The profile is based on the use of partial timing support (PTS) or assisted partial timing sup- port (APTS) from the network architecture as described in [ITU-T G.8275] and definitions described in [ITU-T G.8260]. It is assumed that this profile will be used in well-planned cases where network behaviour and performance can be constrained within well