D.13.4 The F Reply Packet

The F reply packet has the following format:

Fretcode,errno,Ctrl-C flag;call-specific attachment
retcode is the return code of the system call as hexadecimal value.

errno is the errno set by the call, in protocol-specific representation. This parameter can be omitted if the call was successful.

Ctrl-C flag is only sent if the user requested a break. In this case, errno must be sent as well, even if the call was successful. The Ctrl-C flag itself consists of the character C:

          F0,0,C
     

or, if the call was interrupted before the host call has been performed:

          F-1,4,C
     

assuming 4 is the protocol-specific representation of EINTR.