Hierarchy/Derived subclasses
| 420 / 400 |
uspto searches
Patent Apps in 420/400Granted Patents in 420/400
Use the links above or do an advanced search in ppubs for:
(420/400.ccls.)
This will show what classes derive from the input. Ex: entering 43/42.24 shows the derived classes and the search that can be used to find patents or patent applications in those subclasses.