84-556: CDFS may refer to: CDfs , a Linux virtual file system cdfs, a Plan 9 user-space program, is also covered by the above article Compact Disc File System, or ISO 9660 CDFS, an acronym in electrical engineering that has the meaning of inquiring the status of the Schematic completion from the DCM entity (Cand Dracului Faci Schema) Chandra Deep Field South , an astronomical survey in
168-549: A BIOS drive number to the CD drive. The drive number (for INT 13H ) assigned is any of 80 hex ( hard disk emulation), 00 hex ( floppy disk emulation) or an arbitrary number if the BIOS should not provide emulation. Emulation is useful for booting older operating systems from a CD, by making it appear to them as if they were booted from a hard or floppy disk. UEFI systems also accept El Torito records, as platform 0xEF. The record
252-1117: A CD-ROM with Amiga extensions was MakeCD , an Amiga software which Angela Schmidt developed together with Patrick Ohly. El Torito is an extension designed to allow booting a computer from a CD-ROM. It was announced in November 1994 and first issued in January 1995 as a joint proposal by IBM and BIOS manufacturer Phoenix Technologies . According to legend, the El Torito CD/DVD extension to ISO 9660 got its name because its design originated in an El Torito restaurant in Irvine, California ( 33°41′05″N 117°51′09″W / 33.684722°N 117.852547°W / 33.684722; -117.852547 ). The initial two authors were Curtis Stevens, of Phoenix Technologies, and Stan Merkin, of IBM. A 32-bit PC BIOS will search for boot code on an ISO 9660 CD-ROM. The standard allows for booting in two different modes. Either in hard disk emulation when
336-498: A block is always a multiple of 16, and is often a multiple of 128, but is otherwise arbitrary. Characters required for a given script may be spread out over several different, potentially disjunct blocks within the codespace. Each code point is assigned a classification, listed as the code point's General Category property. Here, at the uppermost level code points are categorized as one of Letter, Mark, Number, Punctuation, Symbol, Separator, or Other. Under each category, each code point
420-727: A calendar year and with rare cases where the scheduled release had to be postponed. For instance, in April 2020, a month after version 13.0 was published, the Unicode Consortium announced they had changed the intended release date for version 14.0, pushing it back six months to September 2021 due to the COVID-19 pandemic . Unicode 16.0, the latest version, was released on 10 September 2024. It added 5,185 characters and seven new scripts: Garay , Gurung Khema , Kirat Rai , Ol Onal , Sunuwar , Todhri , and Tulu-Tigalari . Thus far,
504-432: A comprehensive catalog of character properties, including those needed for supporting bidirectional text , as well as visual charts and reference data sets to aid implementers. Previously, The Unicode Standard was sold as a print volume containing the complete core specification, standard annexes, and code charts. However, version 5.0, published in 2006, was the last version printed this way. Starting with version 5.2, only
588-493: A different language opens a Romeo disk, the lack of code page indication will cause non-ASCII characters in file names to become Mojibake . For example, "ü" may become "³". A different OS may encounter a similar problem or refuse to recognize these noncompliant names outright. The same code page problem technically exists in standard ISO 9660, which allows open interpretation of the supplemental and enhanced volume descriptors to any character encoding subject to agreement. However,
672-421: A file attribute that indicates its nature (similar to Unix ). The attributes of a file are stored in the directory entry that describes the file, and optionally in the extended attribute record. To locate a file, the directory names in the file's path can be checked sequentially, going to the location of each directory to obtain the location of the subsequent subdirectory. However, a file can also be located through
756-575: A full semantic duplicate of the Latin alphabet, because legacy CJK encodings contained both "fullwidth" (matching the width of CJK characters) and "halfwidth" (matching ordinary Latin script) characters. The Unicode Bulldog Award is given to people deemed to be influential in Unicode's development, with recipients including Tatsuo Kobayashi , Thomas Milo, Roozbeh Pournader , Ken Lunde , and Michael Everson . The origins of Unicode can be traced back to
840-429: A handful of scripts—often primarily between a given script and Latin characters —not between a large number of scripts, and not with all of the scripts supported being treated in a consistent manner. The philosophy that underpins Unicode seeks to encode the underlying characters— graphemes and grapheme-like units—rather than graphical distinctions considered mere variant glyphs thereof, that are instead best handled by
924-534: A low-surrogate code point forms a surrogate pair in UTF-16 in order to represent code points greater than U+FFFF . In principle, these code points cannot otherwise be used, though in practice this rule is often ignored, especially when not using UTF-16. A small set of code points are guaranteed never to be assigned to characters, although third-parties may make independent use of them at their discretion. There are 66 of these noncharacters : U+FDD0 – U+FDEF and
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#17327825683521008-422: A new "enhanced volume descriptor" data structure. The standard was submitted for ISO 9660:1999 and supposedly fast-tracked, but nothing came out of it. Nevertheless, several operating systems and disc authoring tools (such as Nero Burning ROM , mkisofs and ImgBurn ) now support the addition, under such names as "ISO 9660:1999", "ISO 9660 v2", or "ISO 9660 Level 4". In 2013, the proposal was finally formalized in
1092-535: A project run by Deborah Anderson at the University of California, Berkeley was founded in 2002 with the goal of funding proposals for scripts not yet encoded in the standard. The project has become a major source of proposed additions to the standard in recent years. The Unicode Consortium together with the ISO have developed a shared repertoire following the initial publication of The Unicode Standard : Unicode and
1176-399: A properly engineered design, 16 bits per character are more than sufficient for this purpose. This design decision was made based on the assumption that only scripts and characters in "modern" use would require encoding: Unicode gives higher priority to ensuring utility for the future than to preserving past antiquities. Unicode aims in the first instance at the characters published in
1260-514: A separate system use area where future optional extensions for each file may be specified. High Sierra was adopted in December 1986 (with changes) as an international standard by Ecma International as ECMA-119 and submitted for fast tracking to the ISO , where it was eventually accepted as ISO 9660:1988. Subsequent amendments to the standard were published in 2013 and 2020 . The first 16 sectors of
1344-695: A single space between the file type and ISO 9660 name and some arbitrary number of tabs between the ISO 9660 filename and the extended filename. Unicode Unicode , formally The Unicode Standard , is a text encoding standard maintained by the Unicode Consortium designed to support the use of text in all of the world's writing systems that can be digitized. Version 16.0 of the standard defines 154 998 characters and 168 scripts used in various ordinary, literary, academic, and technical contexts. Many common characters, including numerals, punctuation, and other symbols, are unified within
1428-558: A total of 168 scripts are included in the latest version of Unicode (covering alphabets , abugidas and syllabaries ), although there are still scripts that are not yet encoded, particularly those mainly used in historical, liturgical, and academic contexts. Further additions of characters to the already encoded scripts, as well as symbols, in particular for mathematics and music (in the form of notes and rhythmic symbols), also occur. The Unicode Roadmap Committee ( Michael Everson , Rick McGowan, Ken Whistler, V.S. Umamaheswaran) maintain
1512-654: A universal encoding than the original Unicode architecture envisioned. Version 1.0 of Microsoft's TrueType specification, published in 1992, used the name "Apple Unicode" instead of "Unicode" for the Platform ID in the naming table. The Unicode Consortium is a nonprofit organization that coordinates Unicode's development. Full members include most of the main computer software and hardware companies (and few others) with any interest in text-processing standards, including Adobe , Apple , Google , IBM , Meta (previously as Facebook), Microsoft , Netflix , and SAP . Over
1596-497: Is an extension which adds POSIX file system semantics. The availability of these extension properties allows for better integration with Unix and Unix-like operating systems. The standard takes its name from the fictional town Rock Ridge in Mel Brooks ' film Blazing Saddles . The RRIP extensions are, briefly: The RRIP extensions are built upon SUSP, defining additional tags for support of POSIX semantics, along with
1680-559: Is different from Wikidata All article disambiguation pages All disambiguation pages CDfs ISO 9660 (also known as ECMA -119 ) is a file system for optical disc media. The file system is an international standard available from the International Organization for Standardization (ISO). Since the specification is available for anybody to purchase, implementations have been written for many operating systems . ISO 9660 traces its roots to
1764-447: Is expected to be a disk image containing a FAT filesystem, the filesystem being an EFI System Partition containing the usual \EFI directory. The image should be marked for "no emulation", though it does not actually work like the BIOS "no emulation" mode, in which the BIOS would load the image in memory and execute the code from there. El Torito can also be used to produce CDs which can boot up Linux operating systems, by including
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#17327825683521848-413: Is intended to suggest a unique, unified, universal encoding". In this document, entitled Unicode 88 , Becker outlined a scheme using 16-bit characters: Unicode is intended to address the need for a workable, reliable world text encoding. Unicode could be roughly described as "wide-body ASCII " that has been stretched to 16 bits to encompass the characters of all the world's living languages. In
1932-428: Is more than just a repertoire within which characters are assigned. To aid developers and designers, the standard also provides charts and reference data, as well as annexes explaining concepts germane to various scripts, providing guidance for their implementation. Topics covered by these annexes include character normalization , character composition and decomposition, collation , and directionality . Unicode text
2016-457: Is not padded. There are a total of 2 + (2 − 2 ) = 1 112 064 valid code points within the codespace. (This number arises from the limitations of the UTF-16 character encoding, which can encode the 2 code points in the range U+0000 through U+FFFF except for the 2 code points in the range U+D800 through U+DFFF , which are used as surrogate pairs to encode the 2 code points in
2100-417: Is processed and stored as binary data using one of several encodings , which define how to translate the standard's abstracted codes for characters into sequences of bytes. The Unicode Standard itself defines three encodings: UTF-8 , UTF-16 , and UTF-32 , though several others exist. Of these, UTF-8 is the most widely used by a large margin, in part due to its backwards-compatibility with ASCII . Unicode
2184-480: Is projected to include 4301 new unified CJK characters . The Unicode Standard defines a codespace : a sequence of integers called code points in the range from 0 to 1 114 111 , notated according to the standard as U+0000 – U+10FFFF . The codespace is a systematic, architecture-independent representation of The Unicode Standard ; actual text is processed as binary data via one of several Unicode encodings, such as UTF-8 . In this normative notation,
2268-400: Is then further subcategorized. In most cases, other properties must be used to adequately describe all the characteristics of any given code point. The 1024 points in the range U+D800 – U+DBFF are known as high-surrogate code points, and code points in the range U+DC00 – U+DFFF ( 1024 code points) are known as low-surrogate code points. A high-surrogate code point followed by
2352-486: The Apple ISO 9660 Extensions (file characteristics specific to the classic Mac OS and macOS , such as resource forks , file backup date and more). Compact discs were originally developed for recording musical data, but soon were used for storing additional digital data types because they were equally effective for archival mass data storage . Called CD-ROMs , the lowest level format for these type of compact discs
2436-478: The Apple ISO 9660 Extensions (file characteristics specific to the classic Mac OS and macOS , such as resource forks , file backup date and more). System Use Sharing Protocol (SUSP, IEEE P1281) provides a generic way of including additional properties for any directory entry reachable from the primary volume descriptor (PVD). In an ISO 9660 volume, every directory entry has an optional system use area whose contents are undefined and left to be interpreted by
2520-593: The GRUB bootloader on the CD and following the Multiboot Specification . While the El Torito spec alludes to a "Mac" platform ID, PowerPC-based Apple Macintosh computers don't use it. Joliet is an extension specified and endorsed by Microsoft and has been supported by all versions of its Windows operating system since Windows 95 and Windows NT 4.0 . Its primary focus is the relaxation of
2604-512: The High Sierra Format , which arranged file information in a dense, sequential layout to minimize nonsequential access by using a hierarchical (eight levels of directories deep) tree file system arrangement, similar to UNIX and FAT . To facilitate cross platform compatibility, it defined a minimal set of common file attributes (directory or ordinary file and time of recording) and name attributes (name, extension, and version), and used
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2688-742: The Yellow Book CD-ROM standard, which was so open ended it was leading to diversification and creation of many incompatible data storage methods. The High Sierra Group Proposal ( HSGP ) was released in May 1986, defining a file system for CD-ROMs commonly known as the High Sierra Format. A draft version of this proposal was submitted to the European Computer Manufacturers Association (ECMA) for standardization. With some changes, this led to
2772-571: The typeface , through the use of markup , or by some other means. In particularly complex cases, such as the treatment of orthographical variants in Han characters , there is considerable disagreement regarding which differences justify their own encodings, and which are only graphical variants of other characters. At the most abstract level, Unicode assigns a unique number called a code point to each character. Many issues of visual representation—including size, shape, and style—are intended to be up to
2856-465: The volume descriptor set , a set of one or more volume descriptors terminated with a volume descriptor set terminator . These collectively act as a header for the data area, describing its content (similar to the BIOS parameter block used by FAT , HPFS and NTFS formatted disks). Each volume descriptor is 2048 bytes in size, fitting perfectly into a single Mode 1 or Mode 2 Form 1 sector. They have
2940-578: The 1980s, to a group of individuals with connections to Xerox 's Character Code Standard (XCCS). In 1987, Xerox employee Joe Becker , along with Apple employees Lee Collins and Mark Davis , started investigating the practicalities of creating a universal character set. With additional input from Peter Fenwick and Dave Opstad , Becker published a draft proposal for an "international/multilingual text character encoding system in August 1988, tentatively called Unicode". He explained that "the name 'Unicode'
3024-446: The 4 GiB limit. For example, the free software such as InfraRecorder , ImgBurn and mkisofs as well as Roxio Toast are able to create ISO 9660 file systems that use multi-extent files to store files larger than 4 GiB on appropriate media such as recordable DVDs. Linux supports multiple extents. Since amendment 1 (or ECMA-119 3rd edition, or "JIS X 0606:1998 / ISO 9660:1999"), a much wider variety of file trees can be expressed by
3108-618: The EVD system. There is no longer any character limit (even 8-bit characters are allowed), nor any depth limit or path length limit. There still is a limit on name length, at 207. The character set is no longer enforced, so both sides of the disc interchange need to agree via a different channel. There are several extensions to ISO 9660 that relax some of its limitations. Notable examples include Rock Ridge (Unix-style permissions and longer names), Joliet ( Unicode , allowing non- Latin scripts to be used), El Torito (enables CDs to be bootable ) and
3192-543: The High Sierra Format in the ECMA-119 and ISO 9660 standards were international extensions to allow the format to work better on non-US markets. In order not to create incompatibilities, NISO suspended further work on Z39.60, which had been adopted by NISO members on 28 May 1987. It was withdrawn before final approval, in favour of ISO 9660. JIS X 0606:1998 was passed in Japan in 1998 with much-relaxed file name rules using
3276-567: The ISO's Universal Coded Character Set (UCS) use identical character names and code points. However, the Unicode versions do differ from their ISO equivalents in two significant ways. While the UCS is a simple character map, Unicode specifies the rules, algorithms, and properties necessary to achieve interoperability between different platforms and languages. Thus, The Unicode Standard includes more information, covering in-depth topics such as bitwise encoding, collation , and rendering. It also provides
3360-567: The additional Amiga -bits for files. There is support for attribute "P" that stands for "pure" bit (indicating re-entrant command) and attribute "S" for script bit (indicating batch file ). This includes the protection flags plus an optional comment field. These extensions were introduced by Angela Schmidt with the help of Andrew Young, the primary author of the Rock Ridge Interchange Protocol and System Use Sharing Protocol. The first publicly available software to master
3444-588: The body of the standard: The depth of the directory hierarchy must not exceed 8 (root directory being at level 1), and the path length of any file must not exceed 255. (section 6.8.2.1). The standard also specifies the following name restrictions (sections 7.5 and 7.6): A CD-ROM producer may choose one of the lower Levels of Interchange specified in chapter 10 of the standard, and further restrict file name length from 30 characters to only 8+3 in file identifiers, and 8 in directory identifiers in order to promote interchangeability with implementations that do not implement
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3528-426: The boot information can be accessed directly from the CD media, or in floppy emulation mode where the boot information is stored in an image file of a floppy disk , which is loaded from the CD and then behaves as a virtual floppy disk. This is useful for computers that were designed to boot only from a floppy drive. For modern computers the "no emulation" mode is generally the more reliable method. The BIOS will assign
3612-513: The constellation Fornax See also [ edit ] CDF (disambiguation) Topics referred to by the same term [REDACTED] This disambiguation page lists articles associated with the title CDFS . If an internal link led you here, you may wish to change the link to point directly to the intended article. Retrieved from " https://en.wikipedia.org/w/index.php?title=CDFS&oldid=1209532885 " Category : Disambiguation pages Hidden categories: Short description
3696-496: The core specification, published as a print-on-demand paperback, may be purchased. The full text, on the other hand, is published as a free PDF on the Unicode website. A practical reason for this publication method highlights the second significant difference between the UCS and Unicode—the frequency with which updated versions are released and new characters added. The Unicode Standard has regularly released annual expanded versions, occasionally with more than one version released in
3780-910: The development of a working paper for such a standard. In November 1985, representatives of computer hardware manufacturers gathered at the High Sierra Hotel and Casino (currently called the Golden Nugget Lake Tahoe ) in Stateline, Nevada . This group became known as the High Sierra Group ( HSG ). Present at the meeting were representatives from Apple Computer , AT&T , Digital Equipment Corporation (DEC), Hitachi , LaserData , Microware , Microsoft , 3M , Philips , Reference Technology Inc. , Sony Corporation , TMS Inc. , VideoTools (later Meridian ), Xebec , and Yelick . The meeting report evolved from
3864-420: The directory, and the index of its parent directory path table entry. The parent directory number is a 16-bit number, limiting its range from 1 to 65,535. Directory entries are stored following the location of the root directory entry, where evaluation of filenames is begun. Both directories and files are stored as extents , which are sequential series of sectors. Files and directories are differentiated only by
3948-475: The discretion of the software actually rendering the text, such as a web browser or word processor . However, partially with the intent of encouraging rapid adoption, the simplicity of this original model has become somewhat more elaborate over time, and various pragmatic concessions have been made over the course of the standard's development. The first 256 code points mirror the ISO/IEC 8859-1 standard, with
4032-403: The documentation for mkisofs states filenames up to 103 characters in length do not appear to cause problems. Microsoft has documented it "can use up to 110 characters." The difference lies in whether CDXA extension space is used. Joliet allows Unicode characters to be used for all text fields, which includes file names and the volume name. A "Secondary" volume descriptor with type 2 contains
4116-417: The end of the descriptor set. The primary volume descriptor provides information about the volume, characteristics and metadata, including a root directory record that indicates in which sector the root directory is located. Other fields contain metadata such as the volume's name and creator, along with the size and number of logical blocks used by the file system. Path tables summarize the directory structure of
4200-422: The file system and a volume descriptor set terminator for indicating the end of the descriptor sequence. The volume descriptor set terminator is simply a particular type of volume descriptor with the purpose of marking the end of this set of structures. The primary volume descriptor provides information about the volume, characteristics and metadata, including a root directory record that indicates in which sector
4284-406: The file system are empty and reserved for other uses. The rest begins with a volume descriptor set (a header block which describes the subsequent layout) and then the path tables, directories and files on the disc. An ISO 9660 compliant disc must contain at least one primary volume descriptor describing the file system and a volume descriptor set terminator which is a volume descriptor that marks
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#17327825683524368-529: The filename restrictions inherent with full ISO 9660 compliance. Joliet accomplishes this by supplying an additional set of filenames that are encoded in UCS-2 BE ( UTF-16 BE in practice since Windows 2000). These filenames are stored in a special supplementary volume descriptor, that is safely ignored by ISO 9660-compliant software, thus preserving backward compatibility. The specification only allows filenames to be up to 64 Unicode characters in length. However,
4452-417: The first 32,768 data bytes of the disc (16 sectors of 2,048 bytes each), is unused by ISO 9660 and therefore available for other uses. While it is suggested that they are reserved for use by bootable media , a CD-ROM may contain an alternative file system descriptor in this area, and it is often used by hybrid CDs to offer classic Mac OS -specific and macOS -specific content. The data area begins with
4536-419: The following structure: The data field of a volume descriptor may be subdivided into several fields, with the exact content depending on the type. Redundant copies of each volume descriptor can also be included in case the first copy of the descriptor becomes corrupt. Standard volume descriptor types are the following: An ISO 9660 compliant disc must contain at least one primary volume descriptor describing
4620-401: The following versions of The Unicode Standard have been published. Update versions, which do not include any changes to character repertoire, are signified by the third number (e.g., "version 4.0.1") and are omitted in the table below. The Unicode Consortium normally releases a new version of The Unicode Standard once a year. Version 17.0, the next major version,
4704-528: The form of ISO 9660/Amendment 1, intended to "bring harmonization between ISO 9660 and widely used ' Joliet Specification'." In December 2017, a 3rd Edition of ECMA-119 was published that is technically identical with ISO 9660, Amendment 1. In 2019, ECMA published a 4th version of ECMA-119, integrating the Joliet text as "Annex C". In 2020, ISO published Amendment 2, which adds some minor clarifying matter, but does not add or correct any technical information of
4788-513: The format and meaning of the corresponding system use fields: Amiga Rock Ridge is similar to RRIP, except it provides additional properties used by AmigaOS . It too is built on the SUSP standard by defining an "AS"-tagged system use field. Thus both Amiga Rock Ridge and the POSIX RRIP may be used simultaneously on the same volume. Some of the specific properties supported by this extension are
4872-674: The full standard. All numbers in ISO 9660 file systems except the single byte value used for the GMT offset are unsigned numbers. As the length of a file's extent on disc is stored in a 32 bit value, it allows for a maximum length of just over 4.2 GB (more precisely, one byte less than 4 GiB ). It is possible to circumvent this limitation by using the multi-extent (fragmentation) feature of ISO 9660 Level 3 to create ISO 9660 file systems and single files up to 8 TB. With this, files larger than 4 GiB can be split up into multiple extents (sequential series of sectors), each not exceeding
4956-526: The group. By the end of 1990, most of the work of remapping existing standards had been completed, and a final review draft of Unicode was ready. The Unicode Consortium was incorporated in California on 3 January 1991, and the first volume of The Unicode Standard was published that October. The second volume, now adding Han ideographs, was published in June 1992. In 1996, a surrogate character mechanism
5040-562: The intent of trivializing the conversion of text already written in Western European scripts. To preserve the distinctions made by different legacy encodings, therefore allowing for conversion between them and Unicode without any loss of information, many characters nearly identical to others , in both appearance and intended function, were given distinct code points. For example, the Halfwidth and Fullwidth Forms block encompasses
5124-504: The issue of the initial edition of the ECMA-119 standard in December 1986. The ECMA submitted their standard to the International Standards Organization (ISO) for fast tracking , where it was further refined into the ISO 9660 standard. For compatibility the second edition of ECMA-119 was revised to be equivalent to ISO 9660 in December 1987. ISO 9660:1988 was published in 1988. The main changes from
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#17327825683525208-403: The last two code points in each of the 17 planes (e.g. U+FFFE , U+FFFF , U+1FFFE , U+1FFFF , ..., U+10FFFE , U+10FFFF ). The set of noncharacters is stable, and no new noncharacters will ever be defined. Like surrogates, the rule that these cannot be used is often ignored, although the operation of the byte order mark assumes that U+FFFE will never be the first code point in
5292-637: The list of scripts that are candidates or potential candidates for encoding and their tentative code block assignments on the Unicode Roadmap page of the Unicode Consortium website. For some scripts on the Roadmap, such as Jurchen and Khitan large script , encoding proposals have been made and they are working their way through the approval process. For other scripts, such as Numidian and Rongorongo , no proposal has yet been made, and they await agreement on character repertoire and other details from
5376-675: The modern text (e.g. in the union of all newspapers and magazines printed in the world in 1988), whose number is undoubtedly far below 2 = 16,384. Beyond those modern-use characters, all others may be defined to be obsolete or rare; these are better candidates for private-use registration than for congesting the public list of generally useful Unicode. In early 1989, the Unicode working group expanded to include Ken Whistler and Mike Kernaghan of Metaphor, Karen Smith-Yoshimura and Joan Aliprand of Research Libraries Group , and Glenn Wright of Sun Microsystems . In 1990, Michel Suignard and Asmus Freytag of Microsoft and NeXT 's Rick McGowan had also joined
5460-448: The path table provided by the file system. This path table stores information about each directory, its parent, and its location on disc. Since the path table is stored in a contiguous region, it can be searched much faster than jumping to the particular locations of each directory in the file's path, thus reducing seek time. The standard specifies three nested levels of interchange (paraphrased from section 10): Additional restrictions in
5544-559: The previous environment of a myriad of incompatible character sets , each used within different locales and on different computer architectures. Unicode is used to encode the vast majority of text on the Internet, including most web pages , and relevant Unicode support has become a common consideration in contemporary software development. The Unicode character repertoire is synchronized with ISO/IEC 10646 , each being code-for-code identical with one another. However, The Unicode Standard
5628-419: The primary volume descriptor is guaranteed to be a small subset of ASCII. Apple Computer authored a set of extensions that add ProDOS or HFS / HFS+ (the primary contemporary file systems for the classic Mac OS ) properties to the filesystem. Some of the additional metadata properties include: In order to allow non-Macintosh systems to access Macintosh files on CD-ROMs, Apple chose to use an extension of
5712-402: The primary volume descriptor(s), supplementary volume descriptors or enhanced volume descriptors may be present. Path tables summarize the directory structure of the relevant directory hierarchy. For each directory in the image, the path table provides the directory identifier, the location of the extent in which the directory is recorded, the length of any extended attributes associated with
5796-828: The range U+10000 through U+10FFFF .) The Unicode codespace is divided into 17 planes , numbered 0 to 16. Plane 0 is the Basic Multilingual Plane (BMP), and contains the most commonly used characters. All code points in the BMP are accessed as a single code unit in UTF-16 encoding and can be encoded in one, two or three bytes in UTF-8. Code points in planes 1 through 16 (the supplementary planes ) are accessed as surrogate pairs in UTF-16 and encoded in four bytes in UTF-8 . Within each plane, characters are allocated within named blocks of related characters. The size of
5880-574: The relevant directory hierarchy. For each directory in the image, the path table provides the directory identifier, the location of the extent in which the directory is recorded, the length of any extended attributes associated with the directory, and the index of its parent directory path table entry. There are several extensions to ISO 9660 that relax some of its limitations. Notable examples include Rock Ridge (Unix-style permissions and longer names), Joliet ( Unicode , allowing non- Latin scripts to be used), El Torito (enables CDs to be bootable ) and
5964-410: The root directory is located. Other fields contain the description or name of the volume, and information about who created it and with which application. The size of the logical blocks which the file system uses to segment the volume is also stored in a field inside the primary volume descriptor, as well as the amount of space occupied by the volume (measured in number of logical blocks). In addition to
6048-520: The same information as the Primary one (sector 16 offset 40 bytes), but in UCS-2BE in sector 17, offset 40 bytes. As a result of this, the volume name is limited to 16 characters. Many current PC operating systems are able to read Joliet-formatted media, thus allowing exchange of files between those operating systems even if non-Roman characters are involved (such as Arabic, Japanese or Cyrillic), which
6132-565: The standard ISO 9660 format. Most of the data, other than the Apple specific metadata, remains visible to operating systems that are able to read ISO 9660. For operating systems which do not support any extensions, a name translation file TRANS.TBL must be used. The TRANS.TBL file is a plain ASCII text file. Each line contains three fields, separated by an arbitrary amount of whitespace : Most implementations that create TRANS.TBL files put
6216-499: The standard and are not treated as specific to any given writing system. Unicode encodes 3790 emoji , with the continued development thereof conducted by the Consortium as a part of the standard. Moreover, the widespread adoption of Unicode was in large part responsible for the initial popularization of emoji outside of Japan. Unicode is ultimately capable of encoding more than 1.1 million characters. Unicode has largely supplanted
6300-451: The standard. The following is the rough overall structure of the ISO 9660 file system. Multi-byte values can be stored in three different formats: little-endian , big-endian , and in a concatenation of both types in what the specification calls "both-byte" order. Both-byte order is required in several fields in the volume descriptors and directory records, while path tables can be either little-endian or big-endian. The system area ,
6384-482: The system use area. SUSP defines several common tags and system use fields: Other known SUSP fields include: The Apple extensions do not technically follow the SUSP standard; however the basic structure of the AA and AB fields defined by Apple are forward compatible with SUSP; so that, with care, a volume can use both Apple extensions as well as RRIP extensions. The Rock Ridge Interchange Protocol (RRIP, IEEE P1282)
6468-408: The system. SUSP defines a method to subdivide that area into multiple system use fields, each identified by a two-character signature tag. The idea behind SUSP was that it would enable any number of independent extensions to ISO 9660 to be created and included on a volume without conflicting. It also allows for the inclusion of property data that would otherwise be too large to fit within the limits of
6552-418: The two-character prefix U+ always precedes a written code point, and the code points themselves are written as hexadecimal numbers. At least four hexadecimal digits are always written, with leading zeros prepended as needed. For example, the code point U+00F7 ÷ DIVISION SIGN is padded with two leading zeros, but U+13254 𓉔 EGYPTIAN HIEROGLYPH O004 ( [REDACTED] )
6636-618: The user communities involved. Some modern invented scripts which have not yet been included in Unicode (e.g., Tengwar ) or which do not qualify for inclusion in Unicode due to lack of real-world use (e.g., Klingon ) are listed in the ConScript Unicode Registry , along with unofficial but widely used Private Use Areas code assignments. There is also a Medieval Unicode Font Initiative focused on special Latin medieval characters. Part of these proposals has been already included in Unicode. The Script Encoding Initiative,
6720-640: The years several countries or government agencies have been members of the Unicode Consortium. Presently only the Ministry of Endowments and Religious Affairs (Oman) is a full member with voting rights. The Consortium has the ambitious goal of eventually replacing existing character encoding schemes with Unicode and its standard Unicode Transformation Format (UTF) schemes, as many of the existing schemes are limited in size and scope and are incompatible with multilingual environments. Unicode currently covers most major writing systems in use today. As of 2024 ,
6804-780: Was defined in the Yellow Book specification in 1983. However, this book did not define any format for organizing data on CD-ROMs into logical units such as files , which led to every CD-ROM maker creating its own format. In order to develop a CD-ROM file system standard ( Z39.60 - Volume and File Structure of CDROM for Information Interchange ), the National Information Standards Organization (NISO) set up Standards Committee SC EE (Compact Disc Data Format) in July 1985. In September/ October 1985 several companies invited experts to participate in
6888-416: Was formerly not possible with plain ISO 9660-formatted media. Operating systems which can read Joliet media include: Romeo was developed by Adaptec and allows the use of long filenames up to 128 characters, written directly into the primary volume descriptor using the current code page . This format is built around the workings of Windows 9x and Windows NT "CDFS" drivers. When a Windows installation of
6972-491: Was implemented in Unicode 2.0, so that Unicode was no longer restricted to 16 bits. This increased the Unicode codespace to over a million code points, which allowed for the encoding of many historic scripts, such as Egyptian hieroglyphs , and thousands of rarely used or obsolete characters that had not been anticipated for inclusion in the standard. Among these characters are various rarely used CJK characters—many mainly being used in proper names, making them far more necessary for
7056-483: Was originally designed with the intent of transcending limitations present in all text encodings designed up to that point: each encoding was relied upon for use in its own context, but with no particular expectation of compatibility with any other. Indeed, any two encodings chosen were often totally unworkable when used together, with text encoded in one interpreted as garbage characters by the other. Most encodings had only been designed to facilitate interoperation between
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