我目前正在我的一个项目（ftp 客户端部分）上实现 ftp 协议。我正在关注RFC959
在这个 RFC 中，我面临一个问题：转义字符，事实上，它描述它必须使用转义字符。但我不知道具体的字符是什么。
这是 RFC 关于转义字符的部分：
3.4.1. STREAM MODE
The data is transmitted as a stream of bytes. There is no
restriction on the representation type used; record structures
are allowed.
In a record structured file EOR and EOF will each be indicated
by a two-byte control code. The first byte of the control code
will be all ones, the escape character. The second byte will
have the low order bit on and zeros elsewhere for EOR and the
second low order bit on for EOF; that is, the byte will have
value 1 for EOR and value 2 for EOF. EOR and EOF may be
indicated together on the last byte transmitted by turning both
low order bits on (i.e., the value 3). If a byte of all ones
was intended to be sent as data, it should be repeated in the
second byte of the control code.
If the structure is a file structure, the EOF is indicated by
the sending host closing the data connection and all bytes are
data bytes.
有谁知道是什么性格？
一般来说，你有一些关于如何告诉 FTP 服务器我已经完成发送文件的线索吗？
提前谢谢你。