Occasionally it is important or desirable to remove empty cells from output, particularly when layer filtering is employed. Layer filtering can produce large numbers of empty cells. A large number of empty cells will increase file size and may produce inefficiency in downstream processing operations. Thus, provision for removing empty cells is available from the Empty Cell Filter check box group.
Empty cell filtering is recursive, in that it eliminates empty cells, and cells that contain only instances of empty cells. There are two empty cell filtering operations available.
This filtering operation is performed entirely in memory and is typically very fast. However, it identifies only cells that are made empty due to layer filtering.
The two check boxes separately enable each of these empty cell filtering operations. If one doesn't care about empty cells, neither box should be checked. If one is using layer filtering and just wants a quick pass to remove cells made empty due to layer filtering, pre-filter should be checked. If one wants to remove all empty cells, both pre-filter and post-filter should be checked. This will generally provide the fastest operation. If not using layer filtering, this will be equivalent to checking post-filter only. When using layer filtering, enabling both filters can be much faster that using post-filtering only.