vujnu experimental gismu

x1 is the subtraction-difference of x2 and x3 (and x4 etc.); x1 = x2 - x [ - x4 etc.]

Near-synonymous to selsumji, but better conveys the concept of "subtraction", as opposed to merely "addend", as well as being more convenient for lujvo. See vu'u, sumji, pilji, dilcu, frinu. Proposed rafsi: -vuj-, -vu'u-

In notes:

x1 (number) is the number of hours (pi'e for minutes) that the timezone of location x2 is ahead (before, if x1 is negative) of location/standard x3
x1 is the absolute difference of numbers x2 and x3 ; x1 = |x2 - x