Assembly: System.Data.Linq (in System.Data.Linq.dll)
If attaching as modified, the entity must either declare a version member or must not participate in update conflict checking.
When a new entity is attached, deferred loaders for any child collections (for example, EntitySet collections of entities from associated tables) are initialized. When SubmitChanges is called, members of the child collections are put into an Unmodified state. To update members of a child collection, you must explicitly call Attach and specify that entity.
For more information, see Data Retrieval and CUD Operations in N-Tier Applications (LINQ to SQL).