Required Metadata Fields
On the Details screen of a field you can mark a field as required. When you mark a field as required, the assets that have this Metadata Schema applied to, will not be able to go Live until the required fields have been filled in. If Workflow has been applied to an asset, the approval process will not be completed until the required values have been filled in.
Required fields will be marked with an asterisk on the Metadata screen of an asset, as shown in the figure below, and will display the message currently empty if no metadata has yet been assigned.

A required metadata field