北门锁钥

Explanation: Refers to the North gate on the original lock and key. After the North by means of military importance. 　　Usage: Partial official; as object; that military site 　　Source: Song Kong Pingzhong "Hung On the Court" Volume V: "Kou Lai public keep the north gate, Krupp made by and asked: 'Messire look heavy, why not in the book?' The answer was: 'Lord, on the court without things, the north gate lock and key non-quasi-not '. " 　　Examples: Song Xi "five famous officials toward the hadith": "the emperor to the court without incident, the north gate lock and key, non-quasi-not." Thesaurus:  North Gate of the tube