(8)To ensure an accurate and complete picture of the order book of a trading venue, competent authorities require information on trading sessions in which financial instruments are traded. This information can notably be used to determine when auction periods or continuous trading start and finish and whether orders cause unscheduled circuit breakers. This information is also required to identify how orders will interact, particularly when sessions end at random periods such as auctions. Information on indicative uncrossing prices and volumes would also assist in analysing possible auction manipulation. Given that a single order can impact either the auction uncrossing price, auction uncrossing volume or both, competent authorities need to see the impact of each order on these values. Without this information it would be difficult to identify which order has had the impact on those values. Additionally, a sequence number should be assigned to each relevant event in order to determine the sequence of events when two or more events take place at the same time.