Is chashu a shoulder or belly?

Excuse me, could you please clarify for me? I'm a bit confused about the term "chashu" and its relation to meat cuts. Are you referring to a specific type of pork dish, perhaps a Japanese-style braised pork belly or shoulder? If so, I'm wondering if "chashu" typically refers to the belly portion of the pig or the shoulder? I'm trying to get a better understanding of the dish and its ingredients, so any clarification would be greatly appreciated.