Defining inheritance mappings

Chapter 8 Generating .NET 2.0 Persistent Objects and Windows Applications

NHibernate supports the two basic inheritance mapping strategies:

Table per class hierarchy
Table per subclass
It does not support the "Table per concrete class" mapping strategy.
These strategies all follow the standard inheritance mapping definitions. However, a separate mapping file is generated for each inheritance hierarchy that has a unique mapping strategy. All mappings of subclasses are defined in the mapping file. The mapping file is generated for the root class of the hierarchy.