Validation Code - Where does it go?

I am seeing a lot of messages about overloading the "AddValidationRules()" method but I don't know where it goes? 

protected override void AddValidationRules()

{

    base.AddValidationRules();

    //Add custom validation rules

}

I have created a custom class based on an auto generated Entity class (public class Unit : NetTiers.Entities.Unit) but the extra validation rules I implemented are not being called when I save the entity.

What if Unit might be used by multiple clients with almost certain custom validations on a per client basis?

Individuals will want to add their own custom validation rules that we don't want to share with the others. I am thinking of creating a client tier of inherited classes for those overrides. Or, can you recommend a better solution?

Thanks for the great work! 

Hi.

I have difficult to fire auto the custom validations rules coded in class Customers.cs. I need that the custom validations fires auto when Update is fired from GridView that is linked to the ObjectDataSource. I have see samples like this:

oCustomers.Validate()
if (oCustomers.IsValid)
{....}

This code runs OK with my custom validations. But i don´t need this schema code, because the Update is fired from GridView to the ObjectDataSource.

Thanks.