Settings are values passed during both request and response
that are supposed to alter the default behavior of the client/server.
They can also carry extra information for the protocol.
The settings type/flag are of type u8 (1 byte).
This means there are 256 possible settings.
Values from 0 to 254(0xfe) are reserved for standard settings values.
For your custom settings, value 0xff(255) indicates custom settings.