... makes the filename end in .txt (so that Notepad will open without hassling you; Windows was baffled by the empty filenames of the BNC editions prior to the XML edition). If you choose this you will be asked whether to force .txt onto all files regardless, or only ones which have no file extension at all.
... changes any curly single or double quote marks or apostrophes into straight ones, ellipses into three dots, and dashes into hyphens. (Microsoft's curly apostrophes differ from straight ones.) See also changing a whole set of unwanted characters.
... replaces every end of line line-break with a space. Preserves any true paragraph breaks, which you must ensure are defined (default = <Enter><Enter> -- in other words two line-breaks one after the other with no words between them).