Online Documentation for SQL Manager for SQL server
Setting column defaults
The Default tab allows you to define the default value for the column. You can either select the default object from the list of database defaults or define a default value for the column. The second option is not available for the Computed column type.
Constraint name
This box allows you to set a name for the constraint which is automatically created when you set a default value for the data column. If you leave this field empty, the constraint will be named by the server.