1. A method for structuring complex nested if-then statements in program code executing on data objects in a digital computer to facilitate computer programmer maintenance and enhancement of a billing agent, and to improve program performance, of said program code, comprising: defining for said billing agent a plurality of condition set data objects, each data object representing a billable activity and represented by a plurality of attribute values including division, department, and at least one additional attribute value; organizing said if-then statements as a plurality of logical case statements, said case statements including new division, new department, new attribute value, and no change; for each said case statement, providing a set of binary condition arrays; determining a condition set for a data object; executing on said data object a case statement for which a condition array from said set of binary condition arrays matches said condition set for said data object; and said billing agent executing said case statements to present at a computer output device charges to be made to said division and department for said billable activities.