For the control connection, FTP generally uses ASCII for the network code page, as specified in the FTP RFCs. For the host/ASCII conversion for the control connection, FTP uses either iconv() or the support for single-byte translation tables. However, when EXTENSIONS UTF8 is coded in FTP.DATA, FTP starts the connection in 7-bit ASCII and negotiates a switch to UTF-8 encoding of the control connection, as described in RFC 2640. FTP uses iconv() for the host/UTF-8 conversion.