mislabel
ISO/IEC 8859-1
In June 2004, the ISO/IEC working group responsible for maintaining eight-bit coded character sets disbanded and ceased all maintenance of ISO 8859, including ISO 8859-1, in order to concentrate on the Universal Character Set and Unicode. In computing applications, encodings that provide full UCS support (such as UTF-8 and UTF-16) are finding increasing favor over encodings based on ISO 8859-1.
Coverage
ISO 8859-1 encodes what it refers to as "Latin alphabet no. 1," consisting of 191 characters from the Latin script. This character encoding is used throughout The Americas, Western Europe, Oceania, and much of Africa. It is also commonly used in most standard romanizations of East-Asian languages.Each character is encoded as a single eight-bit code value. These code values can be used in almost any data interchange system to communicate in the following European languages (with a few exceptions due to missing characters, as noted): Modern languages with complete coverage of their alphabet:
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Also, this encoding does not provide the correct character for the apostrophe, and oriented single high quotation marks, although some texts use the spacing grave accent and spacing acute accent which are both part of ISO 8859-1, instead of the 6-shaped/9-shaped quotations marks or apostrophes (and this works reliably with some font styles where all these characters are displayed as slanted wedge glyphs).
See also: Alphabets derived from the Latin
History
ISO 8859-1 was based on the Multinational Character Set used by Digital Equipment Corporation in the popular VT220 terminal. It was developed within ECMA, the European Computer Manufacturers Association, and published in March 1985 as ECMA-94, by which name it is still sometimes known. The second edition of ECMA-94 (June 1986) also included ISO 8859-2, ISO 8859-3, and ISO 8859-4 as part of the specification
Relationship to ISO/IEC 8859-15
Although ISO/IEC 8859-1 has enough characters for most French text, it is missing a few letters that are less common. It is also missing a single-glyph representation for the letter IJ, two Finnish letters used for transcription of some foreign names and in a few loanwords (Š and Ž), typographic quotation marks and dashes, and common symbols such as the euro sign (€) and dagger (†).
In order to provide some of these characters, ISO/IEC 8859-15 was developed as an update of ISO/IEC 8859-1. This required, however, the removal of some infrequently-used characters from ISO/IEC 8859-1, including fraction symbols and letter-free diacritics: ¤, ¦, ¨, ´, ¸, ¼, ½, and ¾.
Codepage layout
Since all 191 characters encoded by ISO/IEC 8859-1 are 'graphic' (ISO's term for characters that are not control codes) and are compatible with most web browsers, they can be shown as glyphs in the following table. Since the space, no-break space, and soft hyphen characters would not normally be visible, they are represented by abbreviations for their names. All other characters are represented literally. Row and column headings indicate the hexadecimal digit combinations to produce the eight-bit code value; e.g., the letter L is at code value 4C.| 007D|}|125}} | ||||||||||||||||
Code values 00–1F, 7F–9F are not assigned to characters by ISO/IEC 8859-1.
The lower range 20 to 7E (the G0 subset) maps exactly to the same coded G0 subset of the ISO 646 US variant (commonly known as ASCII), whose ISO 2022 standard switch sequence is "ESC (B". The higher range A0 to FF (the G1 subset) maps exactly to the same subset initiated by the ISO 2022 standard switch sequence "ESC . A".
Related character maps
The ISO/IEC 8859-1 standard has long been the basis of a number of character maps, also known as character sets, charsets, or code pages, the most popular being ISO-8859-1 (note the extra hyphen) and Windows-1252. Both of these maps are a superset of ISO/IEC 8859-1; they supplement the standard's 191 character assignments by mapping additional characters to at least some portion of the code value ranges 00–1F, 7F, and 80–9F.ISO-8859-1
In 1992, the IANA registered the character map ISO_8859-1:1987, more commonly known by its preferred MIME name of ISO-8859-1 (note the extra hyphen over ISO 8859-1), a superset of ISO 8859-1, for use on the Internet. This map assigns the C0 and C1 control characters to the code values 00–1F, 7F, and 80–9F. It thus provides for 256 characters via every possible 8-bit value.ISO-8859-1 is (according to the standards at least) the default encoding of documents delivered via [
] with a MIME type beginning with "text/". It is the default encoding of the values of certain descriptive HTTP headers, and is the standard encoding used by the X Window System on most Unix machines in locales which use that character set. It was also the basis of the repertoire of characters allowed in HTML 3.2 documents (HTML 4.0, however, is based on Unicode).
Escape sequences (from ISO/IEC 6429 or ISO/IEC 2022) are not to be interpreted in documents labeled as ISO-8859-1 encoded. As well as the canonical name and preferred MIME name mentioned above, the following other aliases are registered for ISO-8859-1: ISO_8859-1, ISO-8859-1, iso-ir-100, csISOLatin1, latin1, l1, IBM819, CP819. ISO-8859-1 was also incorporated as the first 256 code points of ISO/IEC 10646 and Unicode.
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Note that most of these control characters are not made for use in portable ISO-8859-1 encoded plain text documents, but only within specific protocols or devices, except a few ones whose behavior are standardized: TAB (09), LF (0A), CR (0D) and NEL (85); all but the first one are used to encode end of lines or to separate paragraphs, and TAB is often considered equivalent to whitespace. However FF (0C) is commonly accepted in some applications interpreting plain-text documents as an additional ignorable whitespace at the beginning of lines, to mark the position of an explicit page break when printing.
However, some encodings allow using BS (08) to create additional characters by emulating the superposition of multiple characters on printing devices.
Some ISO standards assign specific functions to some controls (for example in ISO 2022) where SO (0E), SI (0F), DLE (10), ESC (1B) and SS2 (8E) are used to control the encoding of characters after them or to switch between multiple encodings.
The NUL character (00) is commonly used as a string terminator in some programming languages, or as a filler in database records that must be ignored and is not part of the encoded text. STX (02) and ETX (03) are commonly used for delimiting frames in some transmission protocols. SUB (1A) is also commonly used as a replacement character to mark errors detected in input transmission streams, and it may be rendered graphically. DC1 (11) and DC3 (13) are commonly used in the XON/XOFF protocol for controlling the transmission speed. Finally, EM (19) or EOT (04) may be used as an end-of-file marker in some text file formats.
The ISO-8859-1/Windows-1252 mixup
It is very common to mislabel text data with the charset label ISO-8859-1, even though the data are really Windows-1252 encoded. In Windows-1252, codes between 0x80 and 0x9F are used for letters and punctuation, whereas they are control codes in ISO-8859-1. Many web browsers and e-mail clients will interpret ISO-8859-1 control codes as Windows-1252 characters in order to accommodate such mislabeling but it is not a standard behaviour and care should be taken to avoid generating these characters in ISO-8859-1 labeled content.HTML 5 requires that documents advertised as ISO-8859-1 actually use the Windows-1252 encoding. If the document uses any character with different meaning in ISO-8859-1 and Windows-1252, that is considered a parse error.
Similar character sets
The Apple Macintosh computer introduced a character encoding called Mac Roman, or Mac-Roman, in 1984. It was meant to be suitable for Western European desktop publishing. It is a superset of ASCII, like ISO-8859-1, and has most of the characters that are in ISO-8859-1 but in a totally different arrangement. A later version, registered with IANA as "Macintosh", replaced the generic currency sign ¤ with the euro sign €. The few printable characters that are in ISO 8859-1 but not in this set are often a source of trouble when editing text on websites using older Macintosh browsers (including the last version of Internet Explorer for Mac). However the extra characters that Windows-1252 has in the C1 codepoint range are all supported in MacRoman and except for the few missing ISO-8859-1 characters a Macintosh can send/receive files (and email) that are encoded/marked as ISO-8859-1 (with the C1 Control Characters) and Windows-1252 by remapping the glyph's codepoint numbers.DOS had code page 850, which had all printable characters that ISO-8859-1 had (albeit in a totally different arrangement) plus the most widely used graphics characters from code page 437.
See also
- Latin characters in Unicode
- ISO/IEC_8859-15 - a derivative of ISO-8859-1
Notes
External links
- ISO/IEC 8859-1:1998
- ISO/IEC 8859-1:1998 - 8-bit single-byte coded graphic character sets, Part 1: Latin alphabet No. 1 (draft dated February 12, 1998, published April 15, 1998)
- Standard ECMA-94: 8-Bit Single Byte Coded Graphic Character Sets - Latin Alphabets No. 1 to No. 4 2nd edition (June 1986)
- ISO-IR 100 Right-Hand Part of Latin Alphabet No.1 (February 1, 1986)
- Windows Code pages
- Differences between ANSI, ISO-8859-1 and MacRoman Character Sets
- The Letter Database
- The ISO 8859 Alphabet Soup - Roman Czyborra's summary of ISO character sets
This article is licensed under the GNU Free Documentation License.
Last updated on Monday September 15, 2008 at 03:11:39 PDT (GMT -0700)
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