Telex, is a convention for encoding Vietnamese text in plain ASCII characters. Originally used for transmitting Vietnamese text over telex systems, it is now a popular input method for computers.
History
The Telex input method is based on a set of rules for transmitting accented Vietnamese text over telex first used in Vietnam during the 1920s and 1930s. Telex services at the time ran over infrastructure that was designed overseas to handle only a basic Latin alphabet, so a message reading "vỡ đê" could easily be misinterpreted as "vợ đẻ". Nguyễn Văn Vĩnh, a prominent journalist and translator, is credited with devising the original set of rules for telex systems. In later decades, common computer systems came with largely the same limitations as the telex infrastructure, namely inadequate support for the large number of characters in Vietnamese. Mnemonics like Telex and Vietnamese Quoted-Readable were adapted for these systems. As a variable-width character encoding, Telex represents a single Vietnamese character as one, two, or three ASCII characters. By contrast, a byte-orientedcode page like VISCIItakes up only one byte per Vietnamese character but requires specialized software or hardware for input. In the 1980s and 1990s, Telex was adopted as a way to type Vietnamese on standard English keyboards. Specialized software converted Telex keystrokes to either precomposed or decomposed Unicode text as the user typed. VietStar was the first such software package to support this entry mode. The Bked editor by Quách Tuấn Ngọc extended Telex with commands such as z, for "ơ". It was further popularized with the input method editorsVietKey, Vietres, and VPSKeys. In 1993, the use of Telex as an input method was standardized in Vietnam as part of TCVN 5712. In the 2000s, Unicode largely supplanted language-specific encodings on modern computer systems and the Internet, limiting Telex's use in text storage and transmission. However, it remains the default input method for many input method editors, with VIQR and VNI offered as alternatives. It also continues to supplement international Morse Code in Vietnamese telegraph transmissions.
To write the pair of keys as two distinct characters, the second character has to be repeated. For example, the Vietnamese word cải xoong must be entered as cari xooong rather than cari xoong.
Tone
Keys added to syllable
Sample input
Sample output
Ngang
z or nothing
ngang
ngang
Huyền
f
huyeenf
huyền
Sắc
s
sawcs
sắc
Hỏi
r
hoir
hỏi
Ngã
x
ngax
ngã
Nặng
j
nawngj
nặng
If more than one tone marking key is pressed, the last one will be used. For example, typing asz will return "a". To write a tone marking key as a normal character, one has to press it twice: her becomes hẻ, while herr becomes her.
