Simulation models are usually built in an objective-driven context. Capturing the relationship between a model and its context is a key issue in Modeling and Simulation (M&S). A better driving of the M&S life cycle requires the objectives, assumptions and constraints in disguise behind this relationship to be explicit. A sound systemic-based foundation is provided here to achieve this goal in a clear abstract form. To this end, we give a thorough development to the concept of experimental frames introduced by the DEVS framework, and we erect a specification hierarchy. An application to fire spreading is shown. This work points out several benefits: firstly, it becomes easier to capture and to manipulate some M&S fundamental and advanced concepts, and then to enhance our understanding about them. Secondly, a significant improvement is gained in the M&S process by systematically accompanying the specification of the system with the specification of the context. Lastly, the formal framework, with both system and context specification hierarchies, provides a methodological guide to the modeling process.