| B | SK | PERFORMING OPERATIONS; TRANSPORTING |
| B28 | KL | WORKING CEMENT, CLAY, OR STONE |
| B28B | UKL | SHAPING CLAY OR OTHER CERAMIC COMPOSITIONS, SLAG OR MIXTURES CONTAINING CEMENTITIOUS MATERIAL, e.g. PLASTER (foundry moulding B22C; working stone or stone-like material B28D; shaping of substances in a plastic state, in general B29C; making layered products not composed wholly of these substances B32B; shaping in situ, see the relevant classes of section E) |
| B28C | UKL | PREPARING CLAY; PRODUCING MIXTURES CONTAINING CLAY OR CEMENTITIOUS MATERIAL, e.g. PLASTER (preparing material for foundry moulds B22C 5/00) |
| B28D | UKL | WORKING STONE OR STONE-LIKE MATERIALS (machinery for, or methods of, mining or quarrying E21C) |