A fundamental milestone for synchronization in data centres will be reached at the ITU-T SG15 (October 2025) with the planned release the first edition of a Supplement on synchronization in data centre. The Supplement puts together considerations on target time sync requirements, suitable solutions, clocks, etc. as agreed by some of the major users and vendors active within the data centre industry. The benefits in distributing synchronizing among servers in a data centre range from minimizing power consumption to guarantee the correctness of operations distributed over multiple servers. These benefits will be particular visible in case such as AI data centres. This talk will summarize efforts done in various bodies, particular focus on the ITU-T Supplement, to define requirements and harmonize solutions that can be implemented within various types of data centres.  The plan is to present in cooperation with partners, the results of an analysis of timing accuracy and latency measurements, with particular emphasis on observability and correlation across distributed systems. These are aspects particularly relevant as data centres evolve toward AI and large-scale distributed systems. Note: speaker to be confirmed