By default, all subforms except the root subform are defined to position content. The root subform always flows content according to the Flow Direction setting of its associated content area. Because the root subform flows content, all subforms nested under the root subform can flow from one form page or content area into the next automatically if required when data is merged.In contrast, when a subform positions content, the area bounded by the subform may expand to accommodate any amount of merged data, but none of the objects in the subform can move from their anchor points. Therefore, if a subform contains objects that merge with variable sizes of data, you must verify that those objects do not expand to the extent that they overrun the area occupied by another object. Any objects that expand in response to data merging, such as a text field, have the potential to be rendered on top of other objects.To avoid this design problem, you can make the subform flow content. A subform that flows content places objects correctly during the data-merging process so that none of its objects are rendered on top of each other.The default subform for the page positions content to support the creation of interactive forms and forms that have a fixed layout. If you are authoring a form that contains subforms that adjust to accommodate data, you need to work with subforms that position content as well as those that flow content. Different techniques are available for working with subforms in this type of form design. The approach you take depends on your experience with creating form designs whose layout adjusts to accommodate data. For more information, see About forms that have a flowable layout.
