(under the class definition) Structure including a module having two opposed faces which extend in a nonparallel relationship transversely of the major surfaces of a barrier in which the module is a component, e.g., keystone block.
SEE OR SEARCH THIS CLASS, SUBCLASS:
270+, for a block with opposed parallel curved faces and nonparallel edge faces.
284+, for a corner block which may have nonparallel joint faces.
574, for a construction with alternating reversed identical form units.
