With no explanation, label text_A→text_B with either "not_related" or "related".
text_A: Charles II of England did not have a brother.
text_B: Pulse code cab signaling is a form of cab signaling technology developed in the United States by the Union Switch and Signal corporation for the Pennsylvania Railroad in the 1920s .. cab signaling. cab signaling. Union Switch and Signal. Union Switch and Signal. Pennsylvania Railroad. Pennsylvania Railroad. The 4-aspect system widely adopted by the PRR and its successor railroads has become the dominant railroad cab signaling system in North America with versions of the technology also being adopted in Europe and rapid transit systems .. cab signaling. cab signaling. In its home territory on former PRR successor Conrail owned lines and on railroads operating under the NORAC Rulebook it is known simply as Cab Signaling System or CSS .. Conrail. Conrail. NORAC. NORAC
not_related.