1. A method implemented with a processor for managing hierarchical layout data, comprising: using at least a processor to perform a process, the process comprising: initiating a hierarchical layout data management process at least by identifying an object, which belongs to a higher hierarchy, and by traversing down the hierarchical layout data to identify a descendent hierarchy, which is situated below the higher hierarchy, based at least in part upon the object identified; maintaining existence information that tracks whether one or more objects exist for the object in the descendent hierarchy in an array of elements, wherein an element in the array of elements indicates whether or not the descendent hierarchy situated below the higher hierarchy contributes to a layer purpose pair that formalizes, for the object, a purpose and a layer for the object; associating the array of elements with one or more containers; and using the array of elements to process a query on the hierarchical layout data based at least in part upon the layer purpose pair.