# 3. Version Control System Fields

Most of the version control system (VCS) fields types are common to both `source-repository` and `source-repository-package` stanzas.

Field Name | source-repository (head|this) | source-repository-package
--- | --- | ---
type | [x] | [x]
location | [x] | [x]
branch | [x] | [x]
tag | [x] | [x]
subdir | [x] (0 or 1) | [x] (0 or 1 for each dependency)
module (CVS only) | [x] | [_]
post-checkout-command | [_] | [x]

## 3.1. VCS kind

Cabal supports specifying different information for various common source control systems. This is the name of the source control system used for a repository. The currently recognised types are:

- `darcs`

- `git`

- `svn`

- `cvs`

- `mercurial` (or alias `hg`)

- `bazaar` (or alias `bzr`)

- `arch`

- `monotone`

- `pijul`

The VCS kind will determine what other fields are appropriate to specify for a particular version control system.

## 3.2. VCS location

The location of the repository, usually a URL but the exact form of this field depends on the repository type. For example:

- for Darcs: `http://code.haskell.org/foo/`

- for Git: `git://github.com/foo/bar.git`

- for CVS: `anoncvs@cvs.foo.org:/cvs`

## 3.3. VCS branch

Many source control systems support the notion of a branch, as a distinct concept from having repositories in separate locations. For example CVS, SVN and git use branches while darcs uses different locations for different branches. If you need to specify a branch to identify a your repository then specify it in this field.

## 3.4. VCS tag

A tag identifies a particular state of a source repository. The exact form of the tag depends on the repository type.

## 3.5. VCS subdirectory

A field of this type is always optional because it defaults to empty, which corresponds to the root directory of the repository and is the same as specifying `.` explicitly.

Some projects put the sources for multiple packages inside a single VCS repository. This field lets you specify the relative path from the root of the repository to the top directory for the package, i.e. the directory containing the package’s `.cabal` file.