| 502 / | HD | CATALYST, SOLID SORBENT, OR SUPPORT THEREFOR: PRODUCT OR PROCESS OF MAKING |
| 100 | DF | CATALYST OR PRECURSOR THEREFOR {12} |
| 300 | DF | .~ Metal, metal oxide or metal hydroxide {10} |
| 340 | DF | .~.~ Of Group II (i.e., alkaline earth, Be, Mg, Zn, Cd or Hg) {2} |
| 343 | | .~.~.~ Of zinc |