it's just characters - it's a string representation of the byte values.
Because you can't type "carriage return" (0x0d as a byte) and "line feed" (0x0a as a byte) values on a keyboard, many languages let you insert them to strings using an "escape character" followed by a normal character which says what byte value is to be generated. Often the escape characters is a backslash, but in this case it's a forward slash.
Common escape sequences would probably include:
/r 0x0d Carriage return
/n 0x0a Line feed
/t 0x09 Tab
// 0x2f /
In this case, the "/xyz" would problem mean "the byte value yz in hexadecimal".