Retirement finances touch upon distinct subject areas or financial domains of client importance, including: investments (i.e., stocks, bonds, mutual funds); real estate; debt; taxes; cash flow (income and expense) analysis; insurance; defined benefits (e.g., social security, traditional pensions). From an analytic perspective, each domain can be formally characterized and modeled using a different class representation, as defined by a domain's unique set of attributes and behaviors. Domain models require definition only at a level of abstraction necessary for decision analysis.