In information systems development models are used to represent real and target enterprise systems. Ideally the enterprise could have two basic enterprise models - an As-Is model an To-Be model that may integrate all representations of the enterprise relevant to information systems development. Although there are many different suggested approaches how to model the enterprise, no consensus exists of what exactly should be the spectrum of model elements and corresponding to them enterprise artifacts for successful enterprise and information systems development. In this paper we propose an approach of identifying core enterprise model constituents for different systems development settings. The approach is based on the integration of professional knowledge regarding artifacts used in various systems development cases with the variations of a continuous requirements engineering framework that combines traditional requirements identification functions with additional continuous audit, monitoring and analytics activities.