The creation of a development process is a challenging task. The application, customization and refinement of generic process models into fine-grained process steps suitable for a specific problem domain requires major work. This paper first reviews a generic framework for requirements engineering as well as a domain-specific framework. It then outlines some basic principles for a methodology that helps the process engineer develop a process model that considers domain knowledge, as well as constraints and priorities for a particular project. The methodology is called REPM (Requirements Engineering Process Model) and uses mathematical definitions to generate an initial process model to be refined in an iterative manner using the feedback of the process designer.