With no explanation, label text_A→text_B with either "not_related" or "related".
text_A: Marilyn Manson plays metal music.
text_B: The world 's navigable airspace is divided into three-dimensional segments , each of which is assigned to a specific class .. airspace. airspace. Most nations adhere to the classification specified by the International Civil Aviation Organization -LRB- ICAO -RRB- and described below , though they might use only some of the classes defined below , and significantly alter the exact rules and requirements .. International Civil Aviation Organization. International Civil Aviation Organization. Similarly , individual nations may also designate Special Use Airspace with further rules for reasons of national security or safety .
not_related.