In an operational architecture view, the needlines that connect operational nodes represent interoperability requirements. Use of the LISI Reference Model begins with the Operational Node Connectivity Description and the articulation of each operational information interchange (e.g., "transfer target folders to support target selection within 15 minutes"). The operational requirement is then further defined in terms of the nature of the information interchange (e.g., "transfer maps, annotated images, text, and graphics"). Based on the nature of the required information interchange and the operational performance parameters that need to be met for mission accomplishment, each needline is labeled with an interoperability level requirement via LISI Reference Model table lookup. This requirement forms the basis for assessing existing or candidate information systems supporting the needline.