(under subclass 452) Subject matter comprising at least two straightedges linked together so as to permit one of the straightedges to assume positions of varying distances from the other while maintaining parallelism with the stationary straightedge.
SEE OR SEARCH THIS CLASS, SUBCLASS:
427, for devices having a bar slidingly mounted on another bar and which may be used for drawing parallel lines.
430+, for base attached parallel type straightedge.
