The main idea is that there is one definitive reference that standardizes how backflow prevention devices are tested and how cross-connection control programs are run. The Manual of Cross-Connection Control, 10th Edition, published by USC, provides the detailed procedures for evaluating devices, including the exact test methods, acceptance criteria, and the steps utilities follow to inspect, test, and maintain cross-connection control programs. Because it lays out the standardized testing and evaluation criteria used by testers and regulators, it serves as the primary technical reference for both device evaluation and cross-connection control procedures. Other sources cover related areas but not the core evaluation methods. AWWA M14 offers guidance on backflow prevention in general, but the USC Manual is the reference specifically focused on the evaluation procedures and program requirements. The Safe Drinking Water Act is regulatory policy at a higher level, not a how-to guide for testing and evaluation. The USC Approved Assembly List is a catalog of devices that have been approved for use, not the instructional guide for how to evaluate devices or implement cross-connection controls.