US PATENT SUBCLASS 52 / 20
.~ With additional enclosure structure; e.g., manhole

Current as of: June, 1999
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52 /   HD   STATIC STRUCTURES (E.G., BUILDINGS)

19  DF  WITH ENTRANCE FOR PERSONS OR OBJECTS IN HORIZONTAL OR INCLINED COVER {2}
20.~ With additional enclosure structure; e.g., manhole

DEFINITION

Classification: 52/20

(under subclass 19) Structure in which the cover is supported by a wall construction enclosing a space which is entered through the opening.

SEE OR SEARCH THIS CLASS, SUBCLASS:

131+, 192+, 198+, 200, 204.1+, 218, 219, 220.1+, 302.1+, and 553 for a building construction with a material (e.g., air or water) port, duct or channel.