The function acts like a bounding box, with the row and column defining the upper left corner, and the width and height extending the box. If width or height are zero (or ommitted) then the function does nothing.
From MS Specifies the formula stored in this cell. All formulas are persisted in R1C1 notation because they are significantly easier to parse and generate than A1-style formulas. The formula is calculated upon reload unless calculation is set to manual. Recalculation of the formula overrides the value in this cell's Value attribute.