Processing of a variable print document corresponding to a plurality of elements, each element having a type, a coverage area and a z-axis value, may be improved by creating a composite elements to replace groups of elements when element types are compatible and when creating composite elements is desirable based at least on the coverage area of the composite element, for example, in relation to the sum of the coverage areas of the elements in the group, and otherwise swapping z-axis values of elements if the elements do not overlap.