OOSC, Part III, Item 2. Placarding - HRCQ Marking

In the Placarding OOS criteria there is only 2- OOS main violations: 50% or more missing & ---a placard that misrepresents the HM /DG being transported. There is only 1 placard for radioactive materials, however there is a white square background with a black border (see 172.527) that is required for HRCQ loads of radioactive materials. The background requirement is not a placard but a requirement for HRCQ loads of radioactive materials. I have had a vehicle displaying only the background white square with no placard (and on an vehicle with an empty cask) and I cannot find anything in the regs that makes his a violation. Also I have had the radioactive placard on a vehicle with no white square background that required it, which is clearly a violation, but since the background square in not a placard it does not seem to meet the OOS violation criteria. However some teach that it is an OOS violation. Perhaps you can address this and or provide some clarification as to the white square background and how it relates to the OOS on placarding for radioactive materials.

Contradiction in what is being taught/practiced.

Clarification in OOS.