where:

c = A commodity group

e = A direction: emis for productions or dest for attractions

ê = The opposite direction to e

o = A coarse external zone (This is the zone being considered).

j = A coarse external zone (This is an index used for summation over all external zones)

i = A coarse internal zone

Xcej = The external (that is, import or export) trip end (tons per year) for commodity group c, direction e, and coarse internal zone j.

Xcêo = The internal (that is, import or export) trip end (tons per year) for commodity group c, direction , and coarse external zone o.

= Proportion of import or export (depending on ) tons of commodity c that go to or come from external zone o in the base year. This value comes from table Zone.ForeignFraction.

= The growth rate of . This value is taken from table Zone.ForeignTrend

y = The time, in years, from the base year to the year for which CUBE Cargo is being run. This is found by subtracting the two control data parameter values.