In an unindexed search, the directories or files to search.

DSearchJob Class

To specify a directory and its subdirectories, add <+> (less than, plus, greater than) following the directory name. 

To specify one or more files, add the filenames to the FoldersToSearch list. This is more efficient than specifying the folder name in FoldersToSearch and the filename in IncludeFilters, because it eliminates the need for a directory scan to locate the file.