Definition
You create building units with a particular validity. The system defaults the validity start date to the current date and the validity end date to 12/31/9999 (unlimited). You can change these dates.
You cannot use the building unit outside of the specified validity period. This means that you cannot assign building units to other building units or to organizational units outside of their specified validity period. It is also impossible to assign patients to them.

If you wish to transfer legacy data from a previous system and wish to assign the "old" cases to building units, you have to set the validity start date such that the building units are valid when the movements of the transferred cases take place.
If you want to shut down a building unit, you should delimit the validity of the building unit accordingly and set the blocking indicator.