DIFF Main Group
E21D 13/00 Large underground chambers; Methods or apparatus for making them (lining E21D11/00)
Introduced: September 1968
Title
Titles differ between systems:
IPC: Large underground chambers; Methods or apparatus for making them
CPC: Large underground chambers; Methods or apparatus for making them (lining E21D11/00)
Full Title
Full titles differ between systems:
IPC:
Large underground chambers; Methods or apparatus for making them
CPC:
Large underground chambers; Methods or apparatus for making them (lining E21D11/00)
Of 2 combined children, 0 exist in both systems.
2 codes exist only in IPC.
Child Classifications
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