rhetorical construct marker - genuine/serious/literal assertion/question/command marker
Place after an interrogative word (such as xu, ma, mo, etc.) in order to indicate that a question (and, in particular, that construct) is being presented rhetorically with no actual desire for an answer (except one that plays along with the purpose). Place after an imperative construct (such as ko) in order to rhetorically command the audience- such as with the English sentence "Tell me about it", which actually indicates emphatic and personal agreement rather than a command/request for the details to be explicated or elaborated. Various grammatical structures can be marked as rhetorical flourishes this way; in this capacity, the word might (but need not) operate in a way similar to pe'a (such as with, maybe, the phrase "for forty days and forty nights" meaning that some event had a long duration and the utterer wishes to reference/bring to mind the Biblical story of Noah's Flood in some way). Of course, whole bridi can be marked by this word. In general, it elevates the understanding of an utterance from literal to something with a purpose or intent and which may not be entirely factual or genuine but, rather, which is being used a tool in the design of a presentation. This word's negative makes it clear that the utterance is to be understood literally or as a genuine, face-value piece of text (although figurative language may still be present- it is only literal in its presentation, so to speak). See also: si'ai