We propose a 2x2 requirement chart enabling effective identification of items in ConOps, a standard provided by IEEE, and establish a methodology how to use it. The main focus of our proposal is to obtain requirements necessary for constructing ConOps without any bias from realization methods and adopted techniques. By properly constructing ConOps through our chart, we are able to focus on the study period in systems engineering, and as a result to reduce the costs in operation period. We developed two identical enterprise systems, each using a different method, and compared the cost in the operation period of each result. The first method, without creating ConOps in the study period, goes through systems architecture development and systems design based on initial requirements provided by the customers, then moves on to implementation period (case 1). The other method creates ConOps using our 2x2 requirement chart, then processes the rest in the same way as case 1 (case 2). Through this experiment, we verified the effectiveness of the proposed requirement chart.