INT 21 - Novell NetWare - CONNECTION SERVICES - SYSTEM LOGOUT
        AH = D7h
Return: AL = error code
Desc:   this function closes the caller's open files, logs it out from all
          file servers, detaches the workstation from all non-default file
          servers, and maps a drive to the default server's SYS:LOGIN directory
Note:   this function is supported by NetWare 4.0+, Advanced NetWare 1.0+, and
          Alloy NTNX
SeeAlso: AH=E3h/SF=14h,AH=F1h