Note that the terminology "Category" is NOT consistent with ASME terminology. The classification of Type B into Categories I, II and III is exactly analogous to the classification of Section III Division 1 construction into Classes 1, 2 and 3. Classes 1, 2 and 3 apply to progressively less important to safety components; Categories I, II and III are progressively less hazardous quantities of radioactivity.

In the writers opinion the introduction of the term new "Category" was unfortunate since the familiar and accepted term "Class" would have been appropriate. Another alternative would have been to divide Type B into Type B1, B2 and B3.

The "Categories" discussed here are completely unrelated to "Shipping Categories I, II or III," also referred to as "Radioactive I, II or III," which apply to hazardous material shipping labels based on the transport index of the radioactive contents and are defined in IAEA SS6 Para 435 or in 49 CFR 172.403(c). Note that for Shipping Categories III is the most severe while for Packaging Categories I is the most severe.