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Generally, a version is a checkpoint at which a particular thing or idea varies from its previous state or condition.
Pertaining to legal documents, and documents in general, this is when a statement or condition is added, removed, or changed. Relating to computers, versioning is a nearly universal practice in the development of software_engineering, in which the version of the software product changes with each modification in the software. Revision control is very useful for anything that uses versions.
= Software engineering =
This is used in practical terms by the consumer, or client, by being able to compare their copy of the software product against another copy, such as the newest version released by the developer. For the programmer team or company, versioning is often used on a file-by-file basis, where individual parts or sectors of the software code are compared and contrasted with newer or older revisions, often in a collaborative Concurrent Versions System. There is no absolute and definite software version schema; it can often vary from software genre to genre, and is very commonly based on the programmer s personal preference.
=Software versioning schemes=
In software, version numbers are a numbering scheme used to allow the software development organization to better track issues and fixes within the field population. It also allows the customer service arm of the organization to know which issues have been discovered and/or fixed in which releases of the software.
==Numerical==
The most common software versioning scheme is a scheme in which different major releases of the software each receive a unique numerical identifier. This is typically expressed as three numbers, separated by periods, such as version 2.4.13. One very commonly followed structure for these numbers is:
: major.minor[.revision[.build]]
In most cases, the first released version of a software product has version 1.0. Numbers below 1 mean alpha or BETA versions, i.e., versions for testing purposes or internal use, or versions that aren t stable enough for general or practical deployment.
In principle, in subsequent releases, the major number is increased when there are significant jumps in functionality, the minor number is incremented when only minor features or significant fixes have been added, and the revision number is incremented when minor bugs are fixed. A typical product might use the numbers 0.9 (for Development stage#Beta software), 0.9.1, 0.9.2, 0.9.3, 1.0, 1.0.1, 1.0.2, 1.1, 1.1.1, 2.0, 2.0.1, 2.0.2, 2.1, 2.1.1, 2.1.2, 2.2, etc. Developers may at times jump (for example) from version 5.0 to 5.5 to indicate that significant features have been added, but not enough to warrant incrementing the major version number.
There is sometimes a fourth, unpublished number which denotes the software build. This scheme is used by Microsoft. Some companies also include the build date. Version numbers may also include letters and other characters, such as Lotus 1-2-3 Release 1a.
Some software packages use more complex versions of this scheme, such as Linux, which uses odd minor version numbers to denote development releases and even minor version numbers to denote stable releases. For example, Linux 2.5 was a development family of the second major design of the Linux kernel, and Linux 2.6 was the stable release family that Linux 2.5 matured into. After the minor version number in the Linux kernel is the release number, in ascending order; for example, Linux 2.4.0 -> Linux 2.4.22. Even further, a trivial version number was added to 2.6.8, making 2.6.8.1 which denoted a very minor change. This fourth number has been made standard since 2.6.11.1.
A different approach is to use the major and minor numbers, along with an alphanumeric string denoting the release type. A release train using this approach might look like 0.5, 0.6, 0.7, 0.8, 0.9 == 1.0b1, 1.0b2 (with some fixes), 1.0b3 (with more fixes) == 1.0rc1 (which, if it s stable enough ) == 1.0. If 1.0rc1 turns out to have bugs which must be fixed, it turns into 1.0rc2, and so on. The important characteristic of this approach is that the first version of a given level (beta, RC, production) must be identical to the last version of the release below it: you cannot make any changes at all from the last beta to the first RC, or from the last RC to production. If you do, you must roll out another release at that lower level.
The purpose of this, of course, is to permit users (or potential adopters) to properly evaluate how much real-world testing a given build of code has actually undergone. If changes are made between, say, 1.3rc4 and the production release of 1.3, then that release -- which asserts that it has had a production-grade level of testing in the real world, in fact contains changes which have not necessarily been tested in the real world at all .
This approach commonly permits the third level of numbering ( change ), but does not apply this level of rigor to changes in that number: 1.3.1, 1.3.2, 1.3.3, 1.3.4... 1.4b1, etc.
Finally, there s a common habit in the commercial software industry (usually, though not always, spurned by non-commercial programmers) to make major jumps in numeric major or minor version numbers for reasons which do not seem (to many members of the program s audience) to merit them: marketing version numbers. This can be seen in several Microsoft products, as well as Sun Solaris and Java Virtual Machine numbering, SCO Unix version numbers, and Corel Word Perfect, as well as the filePro DB/RAD programming package, which went from 2.0 to 3.0 to 4.0 to 4.1 to 4.5 to 4.8 to 5.0, and is about to go to 5.6, with no intervening release. A slightly different version can be seen in AOL s PC client software, which tends to come out *only* as .0 releases (5.0, 6.0, 7.0, etc...) with never a .1 release .
==Date==
The WINE project uses a date versioning scheme, which uses the year followed by the month followed by the day of the release; for example, WINE 20040505 . This is intended to lead into a decimal versioning scheme when WINE 1.0 is released, but assists in keeping track of the large number of development WINE releases until then.
==Other schemes==
Some software producers use different schemes to denote releases of their software. For example, the Microsoft Windows operating system was first labelled with standard numerical version numbers (Windows 1.0 through Windows 3.x), then by years (Windows 95, Windows 98, Windows 2000), and also by alphanumeric codes (Windows Me, Windows XP). The Debian project uses a major/minor versioning scheme for releases of its operating system, but uses code names from the movie Toy Story during development to refer to stable, unstable and testing releases.
Other examples, identifying versions by year (Adobe Illustrator 88, WordPerfect Office 2003), by alphanumeric codes (Macromedia Flash MX, Adobe Photoshop CS2), and by codename (e.g. Mac OS X Tiger).
==Pre-release versions==
Programs that are in a very early development stage are often called alpha software, after the first letter in the Greek alphabet. After they mature but are not yet ready for release, they may be called beta software, after the second letter in the Greek alphabet. Alpha- and beta-version software is often given numerical versions less than 1 (such as 0.9), to suggest their approach toward a public 1.0 release. Software packages which are soon to be released as a particular version may carry that version tag followed by rc-# , indicating the number of the release candidate. When the version is actually released, the rc tag disappears.
==Unusual versioning schemes==
TeX has an idiosyncratic version numbering system. Since version 3, updates have been indicated by adding an extra digit at the end, so that the version number asymptote approaches pi. The current version is 3.141592. This is a reflection of the fact that TeX is now very stable, and only minor updates are anticipated. TeX developer Donald Knuth has stated that the absolutely final change (to be made after my death) will be to change the version number to π, at which point all remaining bugs will become permanent features.
The developers of MAME do not intend to release a version 1.0 of their emulator program. The argument is that it will never be truly finished because there will always be more arcade games.
== Variations ==
In practice, as noted above, product version numbers are subject to marketing considerations. For example, Microsoft Access jumped from version 2.0 to version 7.0, to match the version number of Microsoft Word. Sun s Java programming language has had the versions:
Software may have an internal version number which differs from the version number shown in the product name (and which typically follows version numbering rules more consistently). J2SE 5.0, for example, has the internal version number of 1.5.0, and versions of Windows from 95 on have continued the standard numerical versions internally: Windows 95 is Windows 4.0, 98 is 4.10, 2000 is 5.0 and XP 5.1.
= Files and documents =
Some file system, such as the OpenVMS Filesystem, also keep versions for files.
Versioning amongst documents is relatively similar to the routine used with computers and software engineering, where with each small change in the structure, contents, or conditions, the version number is incremented by 1, or a smaller or larger value, again depending on the personal preference of the Author and the size or importance of changes made.
= See also =
*Product life cycle management *Version control system *Software *Software engineering *Open source
= External links =
*[http://www.cvshome.org/ CVS (Concurrent Versions System)] *[http://www.codeproject.com/system/winvertable.asp Windows Version Numbers] *[http://www.accurev.com/ Accurev]|
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