A model steps along one dimension, and only that dimension can be read at a distance.
Every model steps along one dimension, its primary dimension. Formulas name it x, as in the x axis of a chart. A step is one position along it, counted from 0.
The primary dimension is usually a date dimension, but it does not have to be. A model may step along a column dimension when it declares an order for that column's members.
An offset reads a driver at a step some distance from the current one. Revenue[x=-1] is revenue at the step before this one.
driver Revenue projected Revenue[x=-1] * scenario.growth
An offset that points before the first step or past the last finds no cell and reads as zero. A driver may read itself one step back without making a cycle, because that cell is already computed.
A range reads several steps at once. Revenue[x=-6..-1] is the six steps before this one, and an aggregation function turns them into one value.
driver Trailing forecast AVG(Revenue[x=-6..-1])
Only the primary dimension can be read at a distance. Every other dimension is read at the current slice, or at its rolled-up coordinate.