RFC 318 (rfc318) - Page 2 of 16

Telnet Protocols

RFC 318                     Telnet Protocol                   April 1972


I.  DEFINITION OF THE NETWORK VIRTUAL TERMINAL

   The Network Virtual Terminal (NVT) is a bi-directional character
   device.  The characters are represented by 8 bit codes.  The NVT has
   no timing characteristics.  The character codes 0 through 127 are the
   USASCII codes.  (Note all code values are given in decimal.)  The
   codes 128 through 255 are used for special control signals.  The NVT
   is described as having a printer and a keyboard.  The printer
   responds to incoming data and the keyboard produces outgoing data.

The Printer

   The NVT printer has an unspecified carriage width (common values are
   40, 72, 80, 120, 128, 132).  The printer can produce representations
   of all 95 USASCII graphics (codes 32 through 126).  Of the 33 USASCII
   control codes (0 through 31 and 127) the following 8 have specific
   meaning to the NVT printer.

   NAME                  CODE    MEANING

   NULL (NUL)            0       A no operation.

   BELL (BEL)            7       Produces an audible or visible signal.

   Back Space (BS)       8       Backspaces the printer one character
                                 position.

   Horizontal Tab (HT)   9       Moves the printer to next horizontal
                                 tab stop.

   Line Feed (LF)        10      Moves the printer to next line (keeping
                                 the same horizontal position).

   Vertical Tab (VT)     11      Moves the printer to the next vertical
                                 tab stop.

   Form Feed (FF)        12      Moves the printer to the top of the
                                 next page.

   Carriage Return (CR)  13      Moves the printer to the left margin
                                 of the current line.

   The remaining USASCII codes (1 through 6, 14 through 31, and 127) do
   not cause the NVT printer to take any action.







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