Question: Can you tell Entity Framework to add an extra field for each field of a certain type? For example: Is it possible to generate a ChangedAt datetime field for each boolean field defined in the model, so this

```
public bool Confirmed { get; set; }

```

could result in a table with an additional field `ConfirmedChangedAt` where the value is updated each time the boolean value is changed.

Answer: 
Usually behavior like this should be implemented directly into your business logic and not automatically into the data layer. So I suggest to write something like this:

```
 // entity
 public class Order
 {
     public bool Confirmed { get; set; }  
     public DateTime? ConfirmedAt { get; set; }
 }

 // business logic
 public class OrderManager
 {
     .................
     public void Confirm( Order order )
     {
         // changing of entity status
         order.Confirmed = true;
         order.ConfirmedAt = DateTime.Now;

         // storing new entity status
         _orderRepository.Update( order );
         ................
     }
 }

```
Plain answer no. 
But it's depend on way how you interact with EF (code first, model first,database first). 
If you using EF 6 and code first approach you can use idea of base Entity class

```
public class BaseEntity
{
    public DateTime ChangedAt {get;set;}
}

public class ConcreteEntity : BaseEntity
{
    public string Name {get;set;}
}

```

Now ConcreteEntity has ChangedAt by inheritance.
If this solution not for you, please explain question with more details.