When you edit a table in a database diagram, an asterisk (*) appears after the table name in the title bar to indicate that the table contains changes that have not yet been saved in the database.
This asterisk appears as a result of a change made to a database object, such as a column or index. When you add a modified table to another open diagram, the table appears there with its unsaved changes and an asterisk in its title bar. When you save the table or the diagram, the asterisk disappears.
This indicator appears whenever a database object in the diagram or the diagram layout has an unsaved change. When you save the diagram, the indicator disappears.