What ISPM-15 is and is not
ISPM-15 regulates solid wood packaging material (WPM) used in international trade to reduce the risk of moving timber pests. In practice that means pallets, crates, boxes, skids, cases and dunnage made of solid wood above the thickness threshold are treated and marked under approved programmes. The official mark includes the IPPC symbol, country code, producer facility code and treatment code such as HT.
ISPM-15 is not a definition of seaworthy packaging. It does not size desiccant. It does not specify multimetal VCI grades. It does not prove a crate base is stiff enough for a given centre of gravity. Those are separate engineering jobs that sit beside phytosanitary compliance.