public class ABusinessRule : mmBusinessRule
{ ...
   #region validate specific data type methods

   // fake code, doesn't work
   public string ValidateDuplicateOrder<BusinessType>(
      BusinessType oBusiness, 
      string order, 
      string sku) 
         where BusinessType : ABusinessObject 
         // needs a type ... ABusinessObject<EntityType> ... OrderType1 ...
   {      
      // make data access call common to all business object types
      // deriving from ABusinessObject 
      int recsFound = oBusiness.GetDuplicateOrder(order, sku);
      
      if (recsFound > 0)
         AddErrorProviderWarning(...)
   }   

public class ABusinessRule : mmBusinessRule
{ ...
   #region validate specific data type methods
   
   public string ValidateDuplicateOrder<EntityType>(
      ABusiness<EntityType> oBusiness, 
      string order, 
      string sku) 
         where EntityType : mmBusinessEntity, new()
         // the right type
         // but, what does "new()" do, or mean?
   {      
      int recsFound = oBusiness.GetDuplicateOrder(order, sku);
      
      if (recsFound > 0)
         AddErrorProviderWarning(...)
   }   

public partial class OrderType1Rules : ABusinessRule
{ ...
   public string ValidateDuplicateOrderType1(
      string order, 
      string sku) 
   {
      // note the casting of the business rule's HostObject to a compatible type
      return ValidateDuplicateOrder((OrderType1)this.HostObject, order, sku);
   }