Vietnamese language and computers

Vietnamese alphabet Character encodings There are as many as 46 character encodings for representing the Vietnamese alphabet. Unicode has become the most popular form for many of the world's writing systems, due to its great compatibility and software support. Diacritics may be encoded either as combining characters or as precomposed characters, which are scattered throughout the Latin-1 Supplement, Latin Extended-A, Latin Extended-B, and Latin Extended Additional blocks. The Vietnamese đồng symbol is encoded in the Currency Symbols block. Unicode's coverage of Vietnamese has been subject to several changes since the 1990s. Early versions of Unicode encoded and as and , respectively. In 2001, these two characters were deprecated as duplicate encodings of and ; this change was incorporated into Unicode 3.2, released in 2002. With the 2009 release of Unicode 5.2, and were undeprecated but discouraged. Historically, the Vietnamese language used other characters beyond the modern alphabet. The Middle Vietnamese letter B with flourish (ꞗ) is included in the Latin Extended-D block. The apex is not separately encoded in Unicode, because it derives from the Portuguese tilde, whereas , which derives from the Greek perispomeni, has always been misencoded as a tilde. As a workaround, represents the apex on Wikisource and Wiktionary. For systems that lack support for Unicode, dozens of 8-bit Vietnamese code pages have been designed. Where ASCII is required, such as when ensuring readability in plain text e-mail, Vietnamese letters are often encoded according to Vietnamese Quoted-Readable (VIQR) or VSCII Mnemonic (VSCII-MNEM), though usage of either variable-width scheme has declined dramatically following the adoption of Unicode on the World Wide Web. For instance, support for all above mentioned 8-bit encodings, with the exception of Windows-1258, was dropped from Mozilla software in 2014. Many Vietnamese fonts intended for desktop publishing are encoded in VNI or TCVN3 (VSCII). Popular web browsers lack support for specialty Vietnamese encodings, so any webpage that uses these fonts appears as unintelligible mojibake on systems without them installed. Vietnamese often stacks diacritics, so typeface designers must take care to prevent stacked diacritics from colliding with adjacent letters or lines. When a tone mark is used together with another diacritic, offsetting the tone mark to the right preserves consistency and avoids slowing down saccades. In advertising signage and in cursive handwriting, diacritics often take forms unfamiliar to other Latin alphabets. For example, the lowercase letter I retains its tittle in ì, ỉ, ĩ, and í. These nuances are rarely accounted for in computing environments. Approaches to character encoding Vietnamese writing requires 134 additional letters (between both cases) besides the 52 already present in ASCII. (as in VNI for DOS). • Drop the uppercase letters which are least frequently used, • Drop forms of the letter Y with tone marks, necessitating use of the letter in those circumstances. This approach was rejected by the designers of VISCII on the basis that a character encoding should not attempt to settle a spelling reform issue. Unicode includes over 10,000 '''' characters as part of Unicode's repertoire of CJK Unified Ideographs. Of these characters, 10,082 can be found in the CJK Unified Ideographs Extension B block, while the rest are distributed between the CJK Unified Ideographs, CJK Unified Ideographs Extension A, and CJK Unified Ideographs Extension C blocks. A further 1,028 characters, including over 400 characters specific to the Tày language, are encoded in the CJK Unified Ideographs Extension E block. The characters are taken from the Vietnamese standards TCVN 5773:1993 and TCVN 6909:2001 [error for TCVN 6056:1995?], as well as from research by the Han-Nom Research Institute and other groups. All the characters in TCVN 5773:1993 and about 95% of the characters in TCVN 6909:2001 [error for TCVN 6056:1995?] have corresponding codepoints in Unicode 5.1, though TCVN 5773:1993 itself mapped most of its characters to the Private Use Area of Unicode. Unicode 13.0 added two diacritical characters to the Ideographic Symbols and Punctuation block that were commonly used to indicate borrowed characters in . The two most comprehensive '''' fonts are the Vietnamese Nôm Preservation Foundation's Light and the community-developed HAN NOM A/HAN NOM B, both of which place a large number of unstandardized characters in the Private Use Areas. The Unicode Consortium's Unihan database includes Vietnamese readings of some characters but does not distinguish between Sino-Vietnamese and '''' readings. Like other CJKV writing systems, '''' is traditionally written vertically, from top to bottom and right to left. and may also be annotated using ruby characters, which is the same as chữ Quốc Ngữ for Vietnamese. ==Text input==

), used in Vietnam in the 1960s, seen at Museum of Ho Chi Minh City A purely physical Vietnamese keyboard would be impractical, due to the sheer number of letter-diacritic-diacritic combinations in the alphabet e.g. ờ, ị. Instead, Vietnamese input relies on formulaic software-based keyboard layouts, virtual keyboards, or input methods (also known as IMEs). Keyboard layouts Vietnamese keyboard layouts rely on dead keys to compose letters with diacritics. Most desktop operating systems include a Vietnamese keyboard layout similar to , a Vietnamese national standard. Previously, typewriters used an AZERTY-based Vietnamese layout (AĐERTY). Input methods framework on Unix systems, supports output in six character encodings. The three most common Vietnamese input methods are Telex, VNI, and VIQR. Telex indicates diacritics using letters that are unlikely to appear at the end of a word, while VNI repurposes the number keys or function keys and VIQR repurposes various punctuation marks. The Telex and VIQR conventions originated in an earlier era of telex machines and typewriters, respectively. Support for these input methods is provided by input method editors (IMEs), which are known in Vietnamese as '''', literally "peckers", "typing sets" or "percussion" in more general terms. IMEs may be provided by the operating system, installed as a third-party application, installed as a browser extension, or provided by an individual website in the form of a script. Common third-party applications include GoTiengViet, UniKey, VietKey, VPSKeys, WinVNKey, and xvnkb. On Unix-like operating systems, the IBus and SCIM frameworks both support Vietnamese. IME scripts such as AVIM, Mudim, and VietTyping can be found on most Vietnamese message boards, the Vietnamese Wikipedia, and other text-intensive websites. The Vietnamese Web browser Cốc Cốc comes with an input method built-in. Input methods allow words to be composed in a more flexible order than keyboard layouts allow. For example, to enter the word "" using the TCVN 6064:1995 keyboard layout, one must type , in that order. By contrast, most IMEs permit the user to insert diacritics at the end of the word: in Telex, in VNI, or in VIQR. Some IMEs even allow diacritics to be entered before their base letters. Depending on an IME's implementation, it may also be possible to edit an existing word's diacritics without retyping the word. Some virtual keyboards supplement the standard dead keys with dedicated shortcut keys. For example, with the VIQR keyboard built into iOS, it is possible to add a horn to "U" by tapping either or the dedicated key, which has no analogue on a physical keyboard. Borrowing a feature common amongst Chinese input methods, some Vietnamese IMEs allow one to skip diacritics altogether and instead, after typing the base letters, the user can select the accented word from a candidate list. In order to provide this autocomplete list, the IME may need to communicate with a Web service. Some IMEs also use candidate lists to allow the user to convert text from the Vietnamese alphabet to ', because there is no one-to-one correspondence between alphabetic words and ' characters. ==Other considerations==

Typical Vietnamese text contains a high proportion of compound words. Compound words are never hyphenated in contemporary usage, so spell checkers are limited to checking individual syllables unless a statistical language model is consulted. Vietnamese has rigid spelling rules and few exceptions, so text-to-speech engines may avoid dictionary lookups except when encountering a foreign loan word. TTS engines must account for tones, which are essential to the meaning of any Vietnamese word e.g. má (mother) is a different word to mà (but). Internationalized user interfaces are generally unable to use the full complement of Vietnamese pronouns that would be expected in a traditional social setting, even when much is known about the user. Instead, user interfaces typically use generic pronouns such as and , some of which make potentially incorrect assumptions about the user's age and relationship to other users. For example, when a social media platform notifies a user about a younger user, it may refer to the latter in the third person as instead of , leading the user to misinterpret the notification as a reference to someone else. ==See also==