The process of defining and refining the initial system capabilities is discussed in terms of how the capabilities support the mission/organizational needs. Use of an architectural model and a modeling language such as DoDAF/UPDM or Unified Architecture Framework (UAF) aids in developing the initial technical requirements and refining capability descriptions and potentially promoting capabilities to technical requirements. The development and use of operational views CV-2, OV-1, OV-2, and OV-3 aid in visualizing the relationship between capabilities and requirements. The modeling tool provides a means to document requirements, constraints, and notes for use in preserving the original thought process used to define a capability or operational activity. A critical feature for supporting future peer review.