In our project, we’re sub classing multiple domain classes from a single Reference Data table – i.e. Volume and Weight types. Among other things, the reference data table contains discriminator, code and value columns. The ‘discriminator’ column stores the name of the class and is used by Fluent NHibernate to determine which subclass to instantiate, the ‘value’ column is the full name of the reference data item, and the ‘code’ column is the abbreviated version of the value.