Warning re Databases Created or Restored under Firebird 2.5.1. All users upgrading from Firebird 2.5.1 to a higher sub-release are strongly advised to. Firebird Conference 2011 · Luxembourg Session: Speaker: Character Sets and Firebird Stefan Heymann Page: 1 Character Sets and Unicode in Firebird. UTF- 8 and Unicode FAQby Markus Kuhn. This text is a very comprehensive one- stop information resource. Unicode/UTF- 8 on POSIX systems (Linux, Unix). You. will find here both introductory information for every user, as well as. Unicode now replaces ASCII, ISO 8. EUC at all levels. It. enables users to handle not only practically any script and language. With the UTF- 8 encoding, Unicode can be used in a convenient and. ASCII, like Unix. UTF- 8 is the way in which Unicode is used. Unix, Linux, and similar systems. Listado de Funciones y Métodos. Lista todas las funciones y métodos del manual. Function and Method listing. List of all the functions and methods in the manual. UCS characters equivalent character in target code U+00B5 MICRO SIGN U+03BC GREEK SMALL LETTER MU 0xB5: ISO 8859-1 U+00C5 LATIN CAPITAL LETTER A WITH RING ABOVE. Make sure that you are well. UTF- 8 smoothly. Contents. What are UCS and ISO 1. The international standard ISO 1. Universal Character Set (UCS). UCS is a superset of all other. It guarantees round- trip. This means simply that no. UCS and then. back to its original encoding. This includes not only the Latin, Greek, Cyrillic. Hebrew, Arabic, Armenian, and Georgian scripts, but also Chinese. Japanese and Korean Han ideographs as well as scripts such as. Hiragana, Katakana, Hangul, Devanagari, Bengali, Gurmukhi, Gujarati. Oriya, Tamil, Telugu, Kannada, Malayalam, Thai, Lao, Khmer, Bopomofo. Tibetan, Runic, Ethiopic, Canadian Syllabics, Cherokee, Mongolian. Ogham, Myanmar, Sinhala, Thaana, Yi, and others. For scripts not yet. This includes not. Cuneiform, Hieroglyphs and various Indo- European notations, but even some. Tolkien’s Tengwar and Cirth. UCS also covers a large number of graphical. Te. X, Post. Script, APL, the International Phonetic Alphabet. IPA), MS- DOS, MS- Windows, Macintosh, OCR fonts, as well as many word. The standard continues to be. Ever more exotic and specialized symbols and. The subsets of. 2. UCS. The characters that. BMP are mostly for specialist. Current. plans are that there will never be characters assigned outside the. FFFF, which covers a bit over. The ISO 1. 06. 46- 1 standard was. BMP. A second part ISO 1. BMP. In the 2. 00. ISO 1. 06. 46 standard. A hexadecimal number that represents a UCS or Unicode. U+” as in U+0. 04. Latin capital letter A”. The UCS characters U+0. U+0. 07. F are. identical to those in US- ASCII (ISO 6. IRV) and the range U+0. U+0. 0FF is identical to ISO 8. Latin- 1). The range U+E0. U+F8. FF and also larger ranges outside the BMP are reserved for private. UCS also defines several methods for encoding a string of. UTF- 8 and UTF- 1. Third. edition, International Organization for Standardization, Geneva, 2. The ZIP. file is 8. MB long. These are similar to the non- spacing accent keys on a. A combining character is not a full character by itself. This way, it is possible to place any accent on. The most important accented characters, like those used. UCS to ensure backwards compatibility with older character sets. They. precomposed characters. Precomposed characters are available in. UCS for backwards compatibility with older encodings that have no. ISO 8. 85. 9. The combining- character. This is especially important for scientific notations such. International Phonetic Alphabet. For. example, the German umlaut character . Several. combining characters can be applied when it is necessary to stack. The Thai script, for example, needs up to two combining. Therefore, ISO 1. Level 1. Combining characters and Hangul Jamo characters. They are required to fully support the Korean script including. Middle Korean. These scripts cannot be represented. UCS without support for at least certain combining. One was the ISO 1. International Organization for. Standardization (ISO), the other was the Unicode Project organized by a. US) manufacturers of multi- lingual. Fortunately, the participants of both projects realized in. They joined their efforts and worked together on. Both projects still exist and publish. Unicode. Consortium and ISO/IEC JTC1/SC2 have agreed to keep the code tables of. Unicode and ISO 1. Unicode 1. 1 corresponded to ISO. Unicode 3. 0 corresponded to ISO 1. Unicode. 3. 2 added ISO 1. Unicode 4. 0 corresponds to ISO. Unicode 5. 0 corresponds to ISO 1. All Unicode versions since 2. Unicode 5. 0 is also available online. All characters are at the same. Unicode specifies algorithms for rendering presentation forms. Arabic), handling of bi- directional texts that. Latin and Hebrew, algorithms for sorting and string. There are other closely related ISO standards, for. UCS strings. A nice feature of the ISO 1. CJK example glyphs in five different. Unicode standard shows the CJK ideographs. Chinese variant. There exist several alternatives for. The two most obvious. Unicode text as sequences of either 2 or 4 bytes. The official terms for these encodings are UCS- 2 and UCS- 4. Unless otherwise specified, the most significant byte. Bigendian convention). An ASCII or Latin- 1 file. UCS- 2 file by simply inserting a 0x. ASCII byte. If we want to have a UCS- 4 file, we have. ASCII byte. Strings with these encodings can contain as parts of many. C library function parameters. In addition, the. UNIX tools expects ASCII files and cannot read 1. For these reasons. UCS- 2 is not a suitable external encoding of Unicode in. This means that files and. ASCII characters have the same. ASCII and UTF- 8. Therefore, no. ASCII byte (0x. F) can appear as part of any other character. All further bytes in a multibyte. BF. This allows easy. The. sequence to be used depends on the Unicode number of the character. U- 0. 00. 00. 00. U- 0. 00. 00. 07. F. 0xxxxxxx. U- 0. U- 0. 00. 00. 7FF. U- 0. 00. 00. 80. U- 0. 00. 0FFFF. 1. U- 0. 00. 10. 00. U- 0. 01. FFFFF. 1. U- 0. 02. 00. 00. U- 0. 3FFFFFF. 1. U- 0. 40. 00. 00. U- 7. FFFFFFF. 1. The xxx bit positions are filled with the bits of the. The rightmost x. bit is the least- significant bit. Only the shortest possible multibyte. Note that in multibyte sequences, the number of leading 1 bits. Please do. not write UTF- 8 in any documentation text in other ways (such as utf. UTF. For example, the character U+0. A (line feed) must. UTF- 8 stream only in the form 0x. A, but not. in any of the following five possible overlong forms. E0 0x. 80 0x. 8A. F0 0x. 80 0x. 80 0x. A. 0x. F8 0x. 80 0x. A. 0x. FC 0x. 80 0x. A. Any overlong UTF- 8 sequence could be abused to bypass UTF- 8. All. overlong UTF- 8 sequences start with one of the following byte. Also note that the code positions U+D8. U+DFFF (UTF- 1. 6. U+FFFE and U+FFFF must not occur in normal. UTF- 8 or UCS- 4 data. UTF- 8 decoders should treat them like malformed. It was. born during the evening hours of 1. New Jersey diner. Rob Pike on a placemat. Rob Pike’s UTF- 8 history). It. replaced an earlier attempt to design a FSS/UTF (file system safe UCS. X/Open working. document in August 1. Gary Miller (IBM), Greger Leijonhufvud and. John Entenmann (SMI) as a replacement for the division- heavy UTF- 1. ISO 1. 06. 46- 1. By the end of the. September 1. 99. 2, Pike and Thompson had turned AT& T. Bell Lab’s Plan 9. UTF- 8. They reported about their experience. Winter 1. 99. 3 Technical Conference, San Diego, January 2. Proceedings, pp. FSS/UTF was briefly also referred to as UTF- 2. UTF- 8, and pushed through the standards process. X/Open Joint Internationalization Group XOJIG. If you use the term. UCS”, “ISO 1. 06. Unicode”, this just refers to a mapping. This does not yet specify how to. These are. sequences of 2 bytes and 4 bytes per character, respectively. ISO. 1. 06. 46 was from the beginning designed as a 3. U- 0. 00. 00. 00. U- 7. FFFFFFF). however it took until 2. Basic Multilingual Plane (BMP), that is beyond the first. ISO 1. 06. 46- 2 and Unicode 3. When it became clear that more than 6. Unicode. was turned into a sort of 2. U- 0. 00. 00. 00. U- 0. 01. 0FFFF. This way UTF- 1. Unicode in a way backwards compatible with. UCS- 2. The term UTF- 3. Unicode to describe a 4- byte encoding of the extended. Unicode. UTF- 3. 2 is the exact same thing as UCS- 4, except that. UTF- 3. 2 is never used to represent characters above. U- 0. 01. 0FFFF, while UCS- 4 can cover all 2. U- 7. FFFFFFF. The ISO 1. U- 0. 01. 0FFFF, in order to turn. UCS- 4 and UTF- 3. The. definitions of UTF- 8 in UCS and Unicode differed originally slightly. UCS, up to 6- byte long UTF- 8 sequences were possible to. U- 7. FFFFFFF, while in Unicode only up to. UTF- 8 sequences are defined to represent characters up to. U- 0. 01. 0FFFF. It has become customary to append the letters. BE” (Bigendian, high- byte first) and “LE” (Littleendian, low- byte. Its byte- swapped equivalent. U+FFFE is not a valid Unicode character, therefore it helps to. Bigendian and Littleendian variants of. UTF- 1. 6 and UTF- 3. The difference. between outputting UCS- 4 versus UTF- 3. UTF- 1. 6 versus UCS- 2 lies in. The fallback mechanism for. UTF- 3. 2 (for. characters > U- 0. FFFF) or UCS- 2 (for characters > U+FFFF) even where. UCS- 4 or UTF- 1. Their use. should be avoided. This. practice should definitely not be used on POSIX. On POSIX systems, the locale (and not a magic file- type code). Mixing the two concepts. Also avoid. deprecated characters, e. Also avoid deprecated. Care should be used with. NFKD or NFKC, as semantic information might be lost (for. U+0. 0B2 (SUPERSCRIPT TWO) maps to 2) and extra mark- up. SUP> 2< /SUP> in HTML). This is the case with Ada. Java, TCL, Perl, Python, C#. These facilities were improved with Amendment 1 to ISO C. ISO C 9. 9 standard. These. facilities were designed originally with various East- Asian encodings. They are on one side slightly more sophisticated than what. UCS (handling of “shift sequences”), but. UCS (combining. characters, etc.). UTF- 8 is an example of what the ISO C standard. The type wchar. Therefore, the. ISO C 9. 9 standard was bound by backwards compatibility. It could not. be changed to require wchar. However, the C compiler can at least. To do so, it defines the macro. The year and month refer to the version of. ISO/IEC 1. 06. 46 and its amendments that have been implemented. For. example, . Most popular. ISO 8. 85. 9- 1 and ISO 8. Europe, ISO 8. 85. Greece, KOI- 8. / ISO 8. CP1. 25. 1 in Russia, EUC and Shift- JIS in Japan, BIG5 in Taiwan, etc. UTF- 8 support has improved dramatically. UTF- 8 on a daily basis. HTML files, email messages, etc.). Level. 1 implementation of ISO 1.
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