IPC Subgroup
E21D 19/04 for use in drifting galleries
Introduced: September 1968
Last revised: January 2006
Full Title
Provisional protective covers for working space > for use in drifting galleries
Classification Context
- Section:
- FIXED CONSTRUCTIONS
- Class:
- EARTH OR ROCK DRILLING; MINING
- Subclass:
- SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS