Six lines on an MTC decide whether your weld procedure is valid.
Carbon equivalent first
CE governs preheat. Everything else on the sheet is secondary if the welder is working blind on this number.
Heat number traceability
Every bundle tag should map to a heat on the certificate. If it does not, you have an unverified material on site.
Impact values in cold regions
Charpy results at the right test temperature are the only guard against brittle fracture in exposed structures.