Codes, Standards, and Specifications
The document hierarchy
MT requirements flow down a chain: the contract or purchase order, the construction or product code (ASME BPVC Section VIII, AWS D1.1, API 1104), that code's NDE article (ASME Section V, Article 7 for MT), and the referenced standard practice (ASTM E709 guide, ASTM E1444/E1444M practice, ASTM E3024, or MIL-STD-1949 for legacy work). The governing code controls when documents conflict. Standard practices tell you how to perform the test; the product code or specification supplies acceptance criteria. Personnel qualification is a separate axis: ASNT SNT-TC-1A under the employer's written practice, or CP-189. Level II performs and interprets; Level III establishes techniques and accepts procedures.
What examiners actually ask
Know which document sets acceptance limits versus technique. A limit on linear indications is an acceptance rule; current formulas and particle concentration are technique rules. ASME Section V requires a written procedure demonstrated to a Level III, with technique parameters within the qualified ranges. Know the verification intervals in the practice you cite - ammeter, yoke, light meter, bath checks - and that a specification may be stricter than the code but never looser.
Traps
Questions hinge on the code edition or addenda invoked by the contract; whether a customer specification overrides a general practice (usually yes, when more restrictive); whether a Level II may revise a procedure (typically no - a Level III does); and whether a document is a Guide (recommendations) or a Practice/Test Method (requirements).
Rule of thumb
On conflict, follow contract → code → referenced standard, and apply the more restrictive acceptance criterion. State the acceptance basis on every report; a rejection with no cited criterion cannot be defended.