ColumnAttribute AutoSync
LINQ to SQL: .NET Language-Integrated Query for Relational Data” says (last item in the “Column Attribute” section): “Specifies if the column is automatically synchronized from the value generated by the database on insert or update commands.
public enum AutoSync {
Default = 0, // Automatically choose
Always = 1,
Never = 2,
OnInsert = 3,
OnUpdate = 4
}