It could be argued that IBM Notes and Domino is a multi-value database system like PICK, or that it is an object system like Zope, but it is in fact unique. Whereas the temptation for relational database programmers is to normalize databases, Notes databases must be denormalized. RDBMS developers often find it difficult to conceptualize the difference. It may be useful to think of an IBM Notes document (a 'note') as analogous to an XML document natively stored in a database (although with limitations on the data types and structures available).