In a TAF, the valid period date and time is provided as:

In a TAF (Terminal Aerodrome Forecast), the valid period is represented by two four-digit sets that indicate the start and end times of the forecast period. These two sets are indeed separated by a slash. The first four-digit set represents the day of the month and the start time in UTC from which the TAF is valid, while the second four-digit set indicates the end time in UTC.

This format is crucial for understanding when the forecast is applicable, allowing pilots and meteorologists to interpret and utilize the forecast information accurately during the specified timeframe. It provides a clear demarcation of the forecast's duration, which is essential for flight planning and operational decision-making.

Other formats mentioned do not reflect the standard structure used in TAFs. Hence, the representation of the valid period with two sets separated by a slash accurately conveys the necessary information in a clear and standardized manner.