Enterprise Object Framework (EOF) is an Entity Relational Mapping (ERM) layer that eases data driven application development by abstracting the database schema into Objects. For EOF to know about the parts of the database schema that are important to you, you need to tell it how to map it's Entities to the database tables, and how to map the entities' Attributes to the database's table fields. This process is called Modeling.
WebObjects developers use a graphical tool to create this model. At one time the tool used would have been part of the Apple WebObjects toolset called EOModeler, EOModeler was deprecated with the release of WebObjects 5.3 and eliminated with the release of WebObjects 5.4. The current modeling tool is EntityModeler. EntityModeler is available as a stand-alone tool or as part of the WOLips Eclipse plugin.