³Ô¹Ïtv / ENGINEERING NOTEEvidence sequence: IPC-2221 Insulation Design1EditionLegacy reference, contract and current revision status distinguished.2RequirementApproved equipment and board-design basis recorded.3GeometryWorst-case assembled air and surface paths.4MeaningArithmetic margin only; no automatic safety or compliance judgment.Conceptual drawing. Not to scale; not manufacturing or compliance evidence.