x1 swears / takes an oath, promising/asserting x2 (abstraction), invoking fate x3 (abstraction)
x2 could be a nu-event or ka-action that x1 intends to happen or perform, or a du'u-proposition that x1 swears the truth of. x3 is a fate (typically bad) that x1 invokes on themself should they break the oath. tu'a can be used to raise x3, to swear by a treasured possession (implied fate being loss of that possession), or a deity (implied fate being the wrath of said deity). See dimna, maldimna, nupre, cevni, dapma