To apply Extended Entity Relationship Model (EER) is a good method for representing requirements on information systems, because of its high level of abstraction. Although it is very close to the user, it is not so trivial when some constructs, such as higher order relationships, are used. This paper describes the characterisation and several important results of an experiment performed at our university in order to show some of the difficulties found when novice students and practitioners use ternary relationships. Some special topics in identifying ternary relationships such as the importance of the domain of text and the intersection data are also investigated. In order to guide and help users in the design task, these results are introduced in PANDORA Case Tool, a research project which tries to serve as a methodological assistance tool.