Field help (UVYSTRDAT) 

This represents the start date of the unavailability period. It is possible to define up to 25 periods for the same code.

Caution: Avoid setting multiple consecutive days (e.g., 12/24/2002 to 12/24/2002 and 12/25/2002 to 12/25/2002). Instead, represent the multiple consecutive days as a range (e.g., 12/24/2002 to 12/25/2002).