Double-byte character set

Source: Wikipedia, the free encyclopedia.
"DBCS" redirects here. For other uses, see DBCS (disambiguation).

A double-byte character set (DBCS) is a

65,536 characters). Examples of such languages include Japanese and Chinese. Korean Hangul does not contain as many characters, but KS X 1001 supports both Hangul and Hanja
, and uses two bytes per character.

In CJK computing

The term DBCS traditionally refers to a character encoding where each graphic character is encoded in two bytes.

In an 8-bit code, such as

shift codes
are used to switch between the SBCS and DBCS.

Sometimes, the use of the term "DBCS" can imply an underlying structure that does not comply with

ISO 2022. For example, "DBCS" can sometimes mean a double-byte encoding that is specifically not Extended Unix Code
(EUC).

This original meaning of DBCS is different from what some consider correct usage today. Some insist that these character encodings be properly called

EUC-TW, GB 18030, and UTF-8
use more than two bytes for some characters, and they support one byte for other characters.

Ambiguity

Some people use DBCS to mean the UTF-16 and UTF-8 encodings, while other people use the term DBCS to mean older (pre-Unicode) character encodings that use more than one byte per character. Shift JIS, GB 2312 and Big5 are a few character encodings that can contain more than one byte per character, but even using the term DBCS for these character encodings is incorrect terminology because these character encodings are really variable-width encodings (as are both UTF-16 and UTF-8). Some IBM mainframes do have true DBCS code pages, which contain only the double byte portion of a multi-byte code page.

If a person uses the term "DBCS enablement" for software

East Asian markets using older technology with code pages, or they are planning on using Unicode. Sometimes this term also implies translation
into an East Asian language. Usually "Unicode enablement" means internationalizing software by using Unicode, and "DBCS enablement" means using incompatible character encodings that exist between the various countries in East Asia for internationalizing software. Since Unicode, unlike many other character encodings, supports all the major languages in East Asia, it is generally easier to enable and maintain software that uses Unicode. DBCS (non-Unicode) enablement is usually only desired when much older operating systems or applications do not support Unicode.

TBCS

A triple-byte character set (TBCS) is a character encoding in which characters (including control characters) are encoded in three bytes.

See also

External links

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