Several decades ago, the Hungarian company "Videoton" manufactured a videoterminal for which I couldn't find a Western prototype. It likely existed, as the device had been assigned a "ES" number, similar to the Easter Bloc clones of Western computer hardware. Please note that the VT-340 designation has no relation to DEC VT340.
The distinguishing characteristics were: serial or byte-parallel interface, ASCII-like encoding (or rather KOI-7 for Cyrillic, where Cyrillic letters replaced the lowercase Latin letters) - as opposed to EBCDIC, thus likely no IBM heritage; all control codes were single-byte, no escape sequences; cursor left was ^H (same as backspace, there was no separate key for backspace), the remaining three directions were ^X-^Y-^Z. There also were insert/delete line/char control codes; the direct positioning code was ^A; the board implementing this feature was optional.
Linefeeds (^J) and most other ctrl-characters (of which most did nothing interesting) occupied a character position, displayed as a space by default. The CTRL BLINK mode key would switch between the default mode and the "blinking controls" mode. It was possible to switch the terminal off-line, entering or editing the screen contents, ending with ^C (ETX), then moving the cursor to the beginning of the text to be sent and pressing "SEND".
It is quite probable that the prototype would be from Europe rather than the U.S.
I have asked that question a few times in various Russian fora over the last few years with no definitive answer. Nobody seems to remember what happened in the videoterminal world before DEC VT52.
