Vows Beneath the Moonlight: Opera

"Oath Beneath the Moonlight" is not a widely known title of a traditional Chinese opera. Based on the name, however, one might guess that it is an opera set beneath the moonlight, with a plot centered on an oath. Although I cannot provide details about a specific opera, I can offer some general elements commonly found in opera introductions that might apply to any work titled "Oath Beneath the Moonlight".