What the classification says
A block is split in such a way that more than one nail shank is visible.
How to spot it
Look at each block face. A crack is acceptable in classes A to C ('some splitting permitted'); the line is crossed when more than one nail shank shows through the split.
Why it matters
Splits are normal in used timber and the classification allows some splitting in classes A to C, which causes arguments at the dock. The test in EPAL's wording is mechanical rather than cosmetic: count the nail shanks you can see through the split. One visible shank is tolerated; more than one means the block is no longer holding its nails properly and the pallet is not fit for use. Photograph the block face with a ruler if you need to show a buyer why a pallet was excluded from a lot.
Effect on the pallet's class
Not exchangeable once more than one shank is visible. See Not fit for use for the full criteria.
Repair
Licensed repair only; the block is replaced, not glued.
If no licensed repairer is practical, sell sound timber as non-EPAL wood or send the pallets for recycling.