Explanation
The most important factor that the engineer should consider in selecting a system development methodology for an unprecedented system with unclear or incomplete user and system requirements is the ability to rapidly explore required system functionality. The ability to rapidly explore required system functionality means that the system development methodology can support the elicitation, analysis, validation and verification of the user and system requirements through various techniques, such as use cases, scenarios, prototypes, simulations and tests. The ability to rapidly explore required system functionality can help reduce the uncertainty and ambiguity of the requirements and increase the confidence and satisfaction of the stakeholders. The ability to rapidly prototype the user interface is a less important factor that may not be relevant or applicable to all systems or projects. Access to a large model library and legacy code base is a less important factor that may not be available or suitable for an unprecedented system. A robust ontology for characterizing complex systems is a less important factor that may not be necessary or sufficient for defining the requirements. Direct support for quickly characterizing and prototyping services is a less important factor that may not be relevant or applicable to all systems or projects. References: OMG-Certified Systems Modeling Professional - Model Builder - Advanced (OCUP2-ADV) Examination Guide Version 1.0, Section 4.5