mekso operator: plus or minus, (((a±b)±c)±...±z)
Strictly not "positive or negative" (which is ma'ujani'u vel sim.). This word is general but could easily be replaced by su'ijonaivu'u when the two options are not equivalent (usually when none of the operands are 0). Not preferred in complicated expressions wherein order of operations is important: see su'ifa'uvu'u or su'ifa'u'aivu'u.