However, software was used to work around this limitation as well. File transfer programs are written specifically for the Apple-CAT II's 202 mode, such as "Catsend" and the later "CatFur", periodically paused and reversed transmission direction, so the receiving computer could acknowledge receipt of a stream of data, and, in the case of CatFur, could add a short chat message to the sender in the middle of the one-way file transfer. Many bulletin board systems (BBSs) running CatSend and then CatFur were set up to transfer warez. The 202 CatFur protocol could only be used by a user running another Apple-CAT II.