NHibernate - Generator tag (creating custom IDs for PK)

- NHibernate Docs: Chapter 5. Basic O/R Mapping
http://www.hibernate.org/hib_docs/nhibernate/html/mapping.html

- Understanding NHibernate <generator> element
http://barchitect.blogspot.com/2008/07/nhibernate-generator-and-primary-key.html

- Learning NHibernate: Generating a Primary Key
  http://www.opgenorth.net/Blog/ViewPost.aspx?pageid=1&ItemID=75&mid=27