BIhI argument modifier: indicates dimensionality/length of tuple
Followed immediately by a nonnegative integer n (which is no less than the length of the nearby argument) without "li" prefacing it; otherwise, it is terminated and the (implicit/elided) number assumed is za'u pa. The argument is understood to be a point/formal tuple in a space of at least the 'dimensionality' described by n. Its exact behavior depends on context (for example: being next to a formal tuple versus next to a point in, say, a geometric space). See: https://mw.lojban.org/index.php?title=Extended_Dimensionality_of_Interval_cmavo