除了Nick所说的，您还可以在流式线:并行软件开发的分支模式中找到更多信息

在这个图中，main是主干，rel1- maintenance是分支，1.0是标记。

首先，正如@AndrewFinnell和@KenLiu指出的，在SVN中，目录名称本身没有任何意义——“主干、分支和标记”只是大多数存储库使用的一种常见约定。并不是所有的项目都使用所有的目录(根本不使用“标签”是很常见的)，事实上，没有什么可以阻止您调用任何您想要的名称，尽管打破常规经常会令人困惑。

我将描述分支和标记最常见的使用场景，并给出如何使用它们的示例场景。

Trunk: The main development area. This is where your next major release of the code lives, and generally has all the newest features. Branches: Every time you release a major version, it gets a branch created. This allows you to do bug fixes and make a new release without having to release the newest - possibly unfinished or untested - features. Tags: Every time you release a version (final release, release candidates (RC), and betas) you make a tag for it. This gives you a point-in-time copy of the code as it was at that state, allowing you to go back and reproduce any bugs if necessary in a past version, or re-release a past version exactly as it was. Branches and tags in SVN are lightweight - on the server, it does not make a full copy of the files, just a marker saying "these files were copied at this revision" that only takes up a few bytes. With this in mind, you should never be concerned about creating a tag for any released code. As I said earlier, tags are often omitted and instead, a changelog or other document clarifies the revision number when a release is made.

例如，假设你开始一个新项目。你开始在“主干”中工作，最终将以1.0版本发布。

Trunk / -开发版本，即将发布1.0 分支/ -空

一旦1.0.0完成，你将分支trunk到一个新的“1.0”分支，并创建一个“1.0.0”标记。现在，关于最终1.1版本的工作继续在主干中进行。

Trunk / -开发版本，即将发布1.1 分支/1.0 - 1.0.0发布版本 Tags /1.0.0 - 1.0.0发布版本

You come across some bugs in the code, and fix them in trunk, and then merge the fixes over to the 1.0 branch. You can also do the opposite, and fix the bugs in the 1.0 branch and then merge them back to trunk, but commonly projects stick with merging one-way only to lessen the chance of missing something. Sometimes a bug can only be fixed in 1.0 because it is obsolete in 1.1. It doesn't really matter: you only want to make sure that you don't release 1.1 with the same bugs that have been fixed in 1.0.

Trunk / -开发版本，即将发布1.1 分支/1.0——即将发布的1.0.1版本 Tags /1.0.0 - 1.0.0发布版本

一旦发现了足够多的错误(或者可能是一个严重的错误)，就决定发布1.0.1版本。因此，您从1.0分支创建了一个标记“1.0.1”，并发布了代码。此时，主干将包含1.1，而“1.0”分支包含1.0.1代码。下次你发布1.0版本的更新时，它将是1.0.2。

Trunk / -开发版本，即将发布1.1 分支/1.0——即将发布的1.0.2版 Tags /1.0.0 - 1.0.0发布版本 Tags /1.0.1 - 1.0.1发布版本

最终，你几乎准备好发布1.1，但你想先做一个测试版。在本例中，您可能会执行“1.1”分支和“1.1beta1”标记。现在，关于1.2(或者2.0)的工作在主干中继续进行，而1.1的工作则在“1.1”分支中继续进行。

Trunk / -开发版本，即将发布1.2 分支/1.0——即将发布的1.0.2版 分支/1.1——即将发布的1.1.0版本 Tags /1.0.0 - 1.0.0发布版本 Tags /1.0.1 - 1.0.1发布版本 Tags /1.1beta a1 - 1.1beta1发布版本

一旦发布了1.1 final版本，就可以从“1.1”分支执行“1.1”标记。

如果您愿意，还可以继续维护1.0，在所有三个分支(1.0、1.1和主干)之间移植错误修复。重要的一点是，对于您所维护的软件的每个主版本，都有一个包含该版本的最新代码版本的分支。

分支的另一个用途是用于特性。这是你分支主干(或你的发布分支之一)并独立开发新特性的地方。一旦特性完成，您将其合并并删除分支。

Trunk / -开发版本，即将发布1.2 分支/1.1——即将发布的1.1.0版本 分支/ui-rewrite -实验特性分支

The idea of this is when you're working on something disruptive (that would hold up or interfere with other people from doing their work), something experimental (that may not even make it in), or possibly just something that takes a long time (and you're afraid if it holding up a 1.2 release when you're ready to branch 1.2 from trunk), you can do it in isolation in branch. Generally you keep it up to date with trunk by merging changes into it all the time, which makes it easier to re-integrate (merge back to trunk) when you're finished.

还要注意，我在这里使用的版本控制方案只是众多方案之一。一些团队会将错误修复/维护版本作为1.1、1.2等，并将主要更改作为1。x, 2。x,等等。这里的用法是相同的，但是您可以将分支命名为“1”或“1”。而不是“1.0”或“1.0. X”。(除此之外，语义版本控制是如何进行版本号的一个很好的指南)。

我认为一些混淆来自标记概念和SVN中的实现之间的差异。对于SVN来说，标签是一个分支，它是一个副本。修改标签被认为是错误的，事实上，像TortoiseSVN这样的工具会警告你，如果你试图用../tags/..在路上。

它们没有任何正式的含义。文件夹就是文件夹 SVN。它们是组织项目的一种普遍接受的方式。

The trunk is where you keep your main line of developmemt. The branch folder is where you might create, well, branches, which are hard to explain in a short post. A branch is a copy of a subset of your project that you work on separately from the trunk. Maybe it's for experiments that might not go anywhere, or maybe it's for the next release, which you will later merge back into the trunk when it becomes stable. And the tags folder is for creating tagged copies of your repository, usually at release checkpoints.

但正如我所说，对于SVN，文件夹就是文件夹。分支、主干和标签只是一种约定。

我随意使用“复制”这个词。SVN实际上并不完全复制存储库中的内容。

当我在OpenCV 2计算机视觉应用编程烹饪书的作者的网站上查找时，我发现了这个关于SVN的很棒的教程，我想我应该分享一下。

他有一个关于如何使用SVN的教程，以及短语“trunk”、“tag”和“branch”的含义。

直接引用自他的教程:

The current version of your software project, on which your team is currently working is usually located under a directory called trunk. As the project evolves, the developer updates that version fix bugs, add new features) and submit his changes under that directory. At any given point in time, you may want to freeze a version and capture a snapshot of the software as it is at this stage of the development. This generally corresponds to the official versions of your software, for example, the ones you will deliver to your clients. These snapshots are located under the tags directory of your project. Finally, it is often useful to create, at some point, a new line of development for your software. This happens, for example, when you wish to test an alternative implementation in which you have to modify your software but you do not want to submit these changes to the main project until you decide if you adopt the new solution. The main team can then continue to work on the project while other developer work on the prototype. You would put these new lines of development of the project under a directory called branches.

一般来说(工具不可知的观点)，分支是用于并行开发的机制。一个SCM可以有0到n个分支。Subversion是0。

Trunk is a main branch recommended by Subversion, but you are in no way forced to create it. You could call it 'main' or 'releases', or not have one at all! Branch represents a development effort. It should never be named after a resource (like 'vonc_branch') but after: a purpose 'myProject_dev' or 'myProject_Merge' a release perimeter 'myProjetc1.0_dev'or myProject2.3_Merge' or 'myProject6..2_Patch1'... Tag is a snapshot of files in order to easily get back to that state. The problem is that tag and branch is the same in Subversion. And I would definitely recommend the paranoid approach: you can use one of the access control scripts provided with Subversion to prevent anyone from doing anything but creating new copies in the tags area.

标签是最终的。其内容不应改变。从来没有。永远。你忘了发行通知里的一行字?创建一个新标记。淘汰或删除旧的。

现在，我读了很多关于“在某某分支中合并某某，然后最终在主干分支中合并”的内容。 这就是所谓的合并工作流，这里没有强制性的内容。这并不是因为你有一个主干分支，你必须合并回任何东西。

按照惯例，主干分支可以代表您的开发的当前状态，但这是一个简单的顺序项目，该项目具有:

没有“预先”开发(用于准备下一个下一个版本，这意味着这些更改与当前的“主干”开发不兼容) 没有大规模的重构(用于测试新的技术选择) 没有以前版本的长期维护

因为对于这些场景中的一个(或所有)，你会得到四个“主干”，四个“当前开发”，而不是你在这些并行开发中所做的所有事情都必须合并回“主干”中。