This subclass covers methods or apparatus specific to mining or quarrying. [3]
This subclass does not cover, even though they may be disclosed only for mining or quarrying, drill bits, bore reamers, core taking devices, drilling pipes or rods, handling, racking or connecting arrangements for drilling pipes or rods, counterboring or enlarging drilled holes, flame drilling, or other drilling apparatus, which are covered by subclass Fulltext... Hierarchy... Expanded...E21B. [3]