File Wrapper - Total Number of Pages (FWM_PG_CT) searches for the total page count for the file wrapper of an application or patent.  That is, this particular field code searches for the total number of pages for all of the documents in the file wrapper, combined, that total a specific number or range of numbers.  So if the file wrapper has 4 documents, each with 5 pages, and you search for FWM_PG_CT:20, the application or patent with this file wrapper will be one of the applications or patents returned with the search result.