The MARC-8 charset is a MARC standard used in MARC-21 library records. The MARC formats are standards for the representation and communication of bibliographic and related information in machine-readable form, and they are frequently used in library database systems. The

character encoding Character encoding is the process of assigning numbers to graphical characters, especially the written characters of human language, allowing them to be stored, transmitted, and transformed using digital computers. The numerical values tha ...

now known as MARC-8 was introduced in 1968 as part of the MARC format. Originally based on the

Latin alphabet The Latin alphabet or Roman alphabet is the collection of letters originally used by the ancient Romans to write the Latin language. Largely unaltered with the exception of extensions (such as diacritics), it used to write English and the ...

, from 1979 to 1983 the

JACKPHY In library automation the initialism JACKPHY refers to a group of language scripts not based on Roman characters, specifically: Japanese, Arabic, Chinese, Korean, Persian, Hebrew, and Yiddish. Focus on these seven writing systems by Library of ...

initiative expanded the repertoire to include Japanese, Arabic, Chinese, and Hebrew characters (among others), with the later addition of Cyrillic and Greek scripts. If a character is not representable in MARC-8 of a MARC-21 record, then

UTF-8 UTF-8 is a variable-length character encoding used for electronic communication. Defined by the Unicode Standard, the name is derived from ''Unicode'' (or ''Universal Coded Character Set'') ''Transformation Format 8-bit''. UTF-8 is capable of e ...

must be used instead. UTF-8 has support for many more characters than MARC-8, which is rarely used outside library data.

Technical details

MARC-8 uses a variant of the

ISO-2022 ISO/IEC 2022 ''Information technology—Character code structure and extension techniques'', is an ISO/IEC standard (equivalent to the ECMA standard ECMA-35, the ANSI standard ANSI X3.41 and the Japanese Industrial Standard JIS X 0202) in the f ...

encoding. It uses escape characters to represent characters beyond the 7-bit

ASCII ASCII ( ), abbreviated from American Standard Code for Information Interchange, is a character encoding standard for electronic communication. ASCII codes represent text in computers, telecommunications equipment, and other devices. Because ...

range of characters. It generally uses the same logical

BiDi A bidirectional text contains two text directionalities, right-to-left (RTL) and left-to-right (LTR). It generally involves text containing different types of alphabets, but may also refer to boustrophedon, which is changing text direction in e ...

ordering as

Unicode Unicode, formally The Unicode Standard,The formal version reference is is an information technology standard for the consistent encoding, representation, and handling of text expressed in most of the world's writing systems. The standard, ...

. The combining characters and base characters are in a different order than used in Unicode. The following are some examples. The combining characters are not always stored in reverse order as

Unicode normalization Unicode equivalence is the specification by the Unicode character encoding standard that some sequences of code points represent essentially the same character. This feature was introduced in the standard to allow compatibility with preexisting ...

. The MARC-21 standard describes the MARC-8 Unicode conversion issues in more detail.

Code structure

The ISO/IEC 2022 coding specifies a two-layer mapping between character codes and displayed characters. In MARC-8, character codes from the 7-bit ASCII graphic range (0x20–0x7F) are referred to as "G0" codes, while codes from the "high ASCII" range (0xA0–0xFF) are referred to as the "G1" codes. Graphic character sets are designated and invoked by means of a multiple byte escape sequence consisting of the escape character, an Intermediate character sequence, and a Final character in the form ESC ''I'' ''F''. The following table shows the intermediate byte after the ESC byte (hexadecimal 1B), and the corresponding ASCII characters. The following table shows the final bytes in hexadecimal and the corresponding ASCII characters after the intermediate bytes. The EACC is the only multibyte encoding of MARC-8, it encodes each CJK character in three ASCII bytes. For example, to encode the U+4EBA CJK character (人) you will need the following bytes \x1B\x24\x31\x21\x30\x64 The \x1B\x24\x31 switches to EACC/CJK, and the \x21\x30\x64 corresponds to the U+4EBA.

Custom set extension

In addition to the ISO-2022 character sets, the following custom sets are available too. The byte designation follows the escape byte (hexadecimal 1B). There is no intermediate byte.

References

External links

MARC 21 Specifications for Record Structure, Character Sets, and Exchange Media
- The official MARC-8 standard as maintained by the

US Library of Congress The Library of Congress (LOC) is the research library that officially serves the United States Congress and is the ''de facto'' national library of the United States. It is the oldest federal cultural institution in the country. The library ...

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