The ever increasing demand for more complex and larger software systems stresses the importance of having well-engineered requirements. Requirements Engineering (RE) can no longer be an isolated upfront phase: RE is critical to ensure the success and quality of the delivered system. This paper presents a study of approaches, techniques, and languages for specifying system behavior. From this survey we synthesize a greatest common subset of constructs, which can be adapted for extending the current Project IT-RSL language. The purpose is to use the specifications written in this controlled natural language to enable automatic consistency checking to increase stakeholders engagement in RE tasks related with verification and validation.