As noted above, EAV modeling makes sense for categories of data, such as clinical findings, where attributes are numerous and sparse. Where these conditions do not hold, standard relational modeling (i.e., one column per attribute) is preferable; using EAV does not mean abandoning common sense or principles of good relational design. In clinical record systems, the subschemas dealing with patient demographics and billing are typically modeled conventionally. (While most vendor database schemas are proprietary, VistA, the system used throughout the United States Department of Veterans Affairs (VA) medical system, known as the Veterans Health Administration (VHA), is open-source and its schema is readily inspectable, though it uses a MUMPS database engine rather than a relational database.)