network virtual terminal (NVT)
The virtual network terminal (NVT) is a conversion concept for different codes and data formats. NVT forms a uniform interface to which various terminals and servers involved in communication are connected.
The NVT model is used by Telnet as a vendor-independent terminal supported by all implementations. NVT format conversion ensures that Telnet clients, i.e. user terminals, can work with different Telnet servers and interpret their character sets and control characters. In the NVT model, keystrokes from each Telnet client are converted to NVT format and transmitted to the Telnet server. A corresponding server implementation converts the NVT data and commands into the data format that the system works with. If data is transferred from the Telnet server to the user terminal, the same procedure is followed: The data is first converted to NVT format, then transmitted and converted back to the user terminal font and control characters in the user terminal. They can then be displayed on the screen or printed out.
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The NVT implementations can also have echo functions. This has the advantage that characters entered into the Telnet client and converted are also displayed on the local terminal.
NVT itself works with information units of one byte into which 7-bit and 8-bit codes can be inserted.