Healthcare Information Systems (HIS) are in most cases complex systems that store and manage large amounts of medical data.
When such a HIS is intended to be used in medical research, it presents the system designer with a double challenge: the need for complexity and flexibility at the same time.
In this paper we present a database design pattern along with a Graphical User Interface (GUI) design that empowers the researcher to build metadata structures, which are supported by relational data structures on a database server.