| OA | OB | OC | OD | OE | OF | OH | OI | OK | OL | OM | ON | OP | OR | OS | OT | OU | OV | OX | OY | OZ |
| Index entry | NAICS Code | U.S. NAICS Title |
|---|---|---|
| Ozokerite mining and/or beneficiating | 212399 | All Other Nonmetallic Mineral Mining |
| Ozone machines for water purification manufacturing | 333319 | Other Commercial and Service Industry Machinery Manufacturing |
| OA | OB | OC | OD | OE | OF | OH | OI | OK | OL | OM | ON | OP | OR | OS | OT | OU | OV | OX | OY | OZ |