This feature is new in Domino 6.
Many of the enhancements in Domino Designer 6 extend the properties-box paradigm to make functions easier and more intuitive. One of the most powerful is the creation of a Data Connector and linked fields that connect a form to an external database. This brings a new ease to integrating Domino and relational data sources.
Data Connection Resources (DCRs) bring the technology of Domino Enterprise Connector Services (DECS) into Designer so that you can define a connection to an external data source, such as a relational database, and use the connection to link the fields in a form to fields in the external source. DCRs are reusable in an application and can be shared across applications. ...