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+[[def_alternate_object_database]]alternate object database::
+	Via the alternates mechanism, a <<def_repository,repository>>
+	can inherit part of its <<def_object_database,object database>>
+	from another object database, which is called an "alternate".
+
+[[def_bare_repository]]bare repository::
+	A bare repository is normally an appropriately
+	named <<def_directory,directory>> with a `.git` suffix that does not
+	have a locally checked-out copy of any of the files under
+	revision control. That is, all of the Git
+	administrative and control files that would normally be present in the
+	hidden `.git` sub-directory are directly present in the
+	`repository.git` directory instead,
+	and no other files are present and checked out. Usually publishers of
+	public repositories make bare repositories available.
+
+[[def_blob_object]]blob object::
+	Untyped <<def_object,object>>, e.g. the contents of a file.
+
+[[def_branch]]branch::
+	A "branch" is an active line of development.  The most recent
+	<<def_commit,commit>> on a branch is referred to as the tip of
+	that branch.  The tip of the branch is referenced by a branch
+	<<def_head,head>>, which moves forward as additional development
+	is done on the branch.  A single Git
+	<<def_repository,repository>> can track an arbitrary number of
+	branches, but your <<def_working_tree,working tree>> is
+	associated with just one of them (the "current" or "checked out"
+	branch), and <<def_HEAD,HEAD>> points to that branch.
+
+[[def_cache]]cache::
+	Obsolete for: <<def_index,index>>.
+
+[[def_chain]]chain::
+	A list of objects, where each <<def_object,object>> in the list contains
+	a reference to its successor (for example, the successor of a
+	<<def_commit,commit>> could be one of its <<def_parent,parents>>).
+
+[[def_changeset]]changeset::
+	BitKeeper/cvsps speak for "<<def_commit,commit>>". Since Git does not
+	store changes, but states, it really does not make sense to use the term
+	"changesets" with Git.
+
+[[def_checkout]]checkout::
+	The action of updating all or part of the
+	<<def_working_tree,working tree>> with a <<def_tree_object,tree object>>
+	or <<def_blob_object,blob>> from the
+	<<def_object_database,object database>>, and updating the
+	<<def_index,index>> and <<def_HEAD,HEAD>> if the whole working tree has
+	been pointed at a new <<def_branch,branch>>.
+
+[[def_cherry-picking]]cherry-picking::
+	In <<def_SCM,SCM>> jargon, "cherry pick" means to choose a subset of
+	changes out of a series of changes (typically commits) and record them
+	as a new series of changes on top of a different codebase. In Git, this is
+	performed by the "git cherry-pick" command to extract the change introduced
+	by an existing <<def_commit,commit>> and to record it based on the tip
+	of the current <<def_branch,branch>> as a new commit.
+
+[[def_clean]]clean::
+	A <<def_working_tree,working tree>> is clean, if it
+	corresponds to the <<def_revision,revision>> referenced by the current
+	<<def_head,head>>. Also see "<<def_dirty,dirty>>".
+
+[[def_commit]]commit::
+	As a noun: A single point in the
+	Git history; the entire history of a project is represented as a
+	set of interrelated commits.  The word "commit" is often
+	used by Git in the same places other revision control systems
+	use the words "revision" or "version".  Also used as a short
+	hand for <<def_commit_object,commit object>>.
++
+As a verb: The action of storing a new snapshot of the project's
+state in the Git history, by creating a new commit representing the current
+state of the <<def_index,index>> and advancing <<def_HEAD,HEAD>>
+to point at the new commit.
+
+[[def_commit_object]]commit object::
+	An <<def_object,object>> which contains the information about a
+	particular <<def_revision,revision>>, such as <<def_parent,parents>>, committer,
+	author, date and the <<def_tree_object,tree object>> which corresponds
+	to the top <<def_directory,directory>> of the stored
+	revision.
+
+[[def_commit-ish]]commit-ish (also committish)::
+	A <<def_commit_object,commit object>> or an
+	<<def_object,object>> that can be recursively dereferenced to
+	a commit object.
+	The following are all commit-ishes:
+	a commit object,
+	a <<def_tag_object,tag object>> that points to a commit
+	object,
+	a tag object that points to a tag object that points to a
+	commit object,
+	etc.
+
+[[def_core_git]]core Git::
+	Fundamental data structures and utilities of Git. Exposes only limited
+	source code management tools.
+
+[[def_DAG]]DAG::
+	Directed acyclic graph. The <<def_commit_object,commit objects>> form a
+	directed acyclic graph, because they have parents (directed), and the
+	graph of commit objects is acyclic (there is no <<def_chain,chain>>
+	which begins and ends with the same <<def_object,object>>).
+
+[[def_dangling_object]]dangling object::
+	An <<def_unreachable_object,unreachable object>> which is not
+	<<def_reachable,reachable>> even from other unreachable objects; a
+	dangling object has no references to it from any
+	reference or <<def_object,object>> in the <<def_repository,repository>>.
+
+[[def_detached_HEAD]]detached HEAD::
+	Normally the <<def_HEAD,HEAD>> stores the name of a
+	<<def_branch,branch>>, and commands that operate on the
+	history HEAD represents operate on the history leading to the
+	tip of the branch the HEAD points at.  However, Git also
+	allows you to <<def_checkout,check out>> an arbitrary
+	<<def_commit,commit>> that isn't necessarily the tip of any
+	particular branch.  The HEAD in such a state is called
+	"detached".
++
+Note that commands that operate on the history of the current branch
+(e.g. `git commit` to build a new history on top of it) still work
+while the HEAD is detached. They update the HEAD to point at the tip
+of the updated history without affecting any branch.  Commands that
+update or inquire information _about_ the current branch (e.g. `git
+branch --set-upstream-to` that sets what remote-tracking branch the
+current branch integrates with) obviously do not work, as there is no
+(real) current branch to ask about in this state.
+
+[[def_directory]]directory::
+	The list you get with "ls" :-)
+
+[[def_dirty]]dirty::
+	A <<def_working_tree,working tree>> is said to be "dirty" if
+	it contains modifications which have not been <<def_commit,committed>> to the current
+	<<def_branch,branch>>.
+
+[[def_evil_merge]]evil merge::
+	An evil merge is a <<def_merge,merge>> that introduces changes that
+	do not appear in any <<def_parent,parent>>.
+
+[[def_fast_forward]]fast-forward::
+	A fast-forward is a special type of <<def_merge,merge>> where you have a
+	<<def_revision,revision>> and you are "merging" another
+	<<def_branch,branch>>'s changes that happen to be a descendant of what
+	you have. In such a case, you do not make a new <<def_merge,merge>>
+	<<def_commit,commit>> but instead just update to his
+	revision. This will happen frequently on a
+	<<def_remote_tracking_branch,remote-tracking branch>> of a remote
+	<<def_repository,repository>>.
+
+[[def_fetch]]fetch::
+	Fetching a <<def_branch,branch>> means to get the
+	branch's <<def_head_ref,head ref>> from a remote
+	<<def_repository,repository>>, to find out which objects are
+	missing from the local <<def_object_database,object database>>,
+	and to get them, too.  See also linkgit:git-fetch[1].
+
+[[def_file_system]]file system::
+	Linus Torvalds originally designed Git to be a user space file system,
+	i.e. the infrastructure to hold files and directories. That ensured the
+	efficiency and speed of Git.
+
+[[def_git_archive]]Git archive::
+	Synonym for <<def_repository,repository>> (for arch people).
+
+[[def_gitfile]]gitfile::
+	A plain file `.git` at the root of a working tree that
+	points at the directory that is the real repository.
+
+[[def_grafts]]grafts::
+	Grafts enables two otherwise different lines of development to be joined
+	together by recording fake ancestry information for commits. This way
+	you can make Git pretend the set of <<def_parent,parents>> a <<def_commit,commit>> has
+	is different from what was recorded when the commit was
+	created. Configured via the `.git/info/grafts` file.
++
+Note that the grafts mechanism is outdated and can lead to problems
+transferring objects between repositories; see linkgit:git-replace[1]
+for a more flexible and robust system to do the same thing.
+
+[[def_hash]]hash::
+	In Git's context, synonym for <<def_object_name,object name>>.
+
+[[def_head]]head::
+	A <<def_ref,named reference>> to the <<def_commit,commit>> at the tip of a
+	<<def_branch,branch>>.  Heads are stored in a file in
+	`$GIT_DIR/refs/heads/` directory, except when using packed refs. (See
+	linkgit:git-pack-refs[1].)
+
+[[def_HEAD]]HEAD::
+	The current <<def_branch,branch>>.  In more detail: Your <<def_working_tree,
+	working tree>> is normally derived from the state of the tree
+	referred to by HEAD.  HEAD is a reference to one of the
+	<<def_head,heads>> in your repository, except when using a
+	<<def_detached_HEAD,detached HEAD>>, in which case it directly
+	references an arbitrary commit.
+
+[[def_head_ref]]head ref::
+	A synonym for <<def_head,head>>.
+
+[[def_hook]]hook::
+	During the normal execution of several Git commands, call-outs are made
+	to optional scripts that allow a developer to add functionality or
+	checking. Typically, the hooks allow for a command to be pre-verified
+	and potentially aborted, and allow for a post-notification after the
+	operation is done. The hook scripts are found in the
+	`$GIT_DIR/hooks/` directory, and are enabled by simply
+	removing the `.sample` suffix from the filename. In earlier versions
+	of Git you had to make them executable.
+
+[[def_index]]index::
+	A collection of files with stat information, whose contents are stored
+	as objects. The index is a stored version of your
+	<<def_working_tree,working tree>>. Truth be told, it can also contain a second, and even
+	a third version of a working tree, which are used
+	when <<def_merge,merging>>.
+
+[[def_index_entry]]index entry::
+	The information regarding a particular file, stored in the
+	<<def_index,index>>. An index entry can be unmerged, if a
+	<<def_merge,merge>> was started, but not yet finished (i.e. if
+	the index contains multiple versions of that file).
+
+[[def_master]]master::
+	The default development <<def_branch,branch>>. Whenever you
+	create a Git <<def_repository,repository>>, a branch named
+	"master" is created, and becomes the active branch. In most
+	cases, this contains the local development, though that is
+	purely by convention and is not required.
+
+[[def_merge]]merge::
+	As a verb: To bring the contents of another
+	<<def_branch,branch>> (possibly from an external
+	<<def_repository,repository>>) into the current branch.  In the
+	case where the merged-in branch is from a different repository,
+	this is done by first <<def_fetch,fetching>> the remote branch
+	and then merging the result into the current branch.  This
+	combination of fetch and merge operations is called a
+	<<def_pull,pull>>.  Merging is performed by an automatic process
+	that identifies changes made since the branches diverged, and
+	then applies all those changes together.  In cases where changes
+	conflict, manual intervention may be required to complete the
+	merge.
++
+As a noun: unless it is a <<def_fast_forward,fast-forward>>, a
+successful merge results in the creation of a new <<def_commit,commit>>
+representing the result of the merge, and having as
+<<def_parent,parents>> the tips of the merged <<def_branch,branches>>.
+This commit is referred to as a "merge commit", or sometimes just a
+"merge".
+
+[[def_object]]object::
+	The unit of storage in Git. It is uniquely identified by the
+	<<def_SHA1,SHA-1>> of its contents. Consequently, an
+	object cannot be changed.
+
+[[def_object_database]]object database::
+	Stores a set of "objects", and an individual <<def_object,object>> is
+	identified by its <<def_object_name,object name>>. The objects usually
+	live in `$GIT_DIR/objects/`.
+
+[[def_object_identifier]]object identifier::
+	Synonym for <<def_object_name,object name>>.
+
+[[def_object_name]]object name::
+	The unique identifier of an <<def_object,object>>.  The
+	object name is usually represented by a 40 character
+	hexadecimal string.  Also colloquially called <<def_SHA1,SHA-1>>.
+
+[[def_object_type]]object type::
+	One of the identifiers "<<def_commit_object,commit>>",
+	"<<def_tree_object,tree>>", "<<def_tag_object,tag>>" or
+	"<<def_blob_object,blob>>" describing the type of an
+	<<def_object,object>>.
+
+[[def_octopus]]octopus::
+	To <<def_merge,merge>> more than two <<def_branch,branches>>.
+
+[[def_origin]]origin::
+	The default upstream <<def_repository,repository>>. Most projects have
+	at least one upstream project which they track. By default
+	'origin' is used for that purpose. New upstream updates
+	will be fetched into <<def_remote_tracking_branch,remote-tracking branches>> named
+	origin/name-of-upstream-branch, which you can see using
+	`git branch -r`.
+
+[[def_overlay]]overlay::
+	Only update and add files to the working directory, but don't
+	delete them, similar to how 'cp -R' would update the contents
+	in the destination directory.  This is the default mode in a
+	<<def_checkout,checkout>> when checking out files from the
+	<<def_index,index>> or a <<def_tree-ish,tree-ish>>.  In
+	contrast, no-overlay mode also deletes tracked files not
+	present in the source, similar to 'rsync --delete'.
+
+[[def_pack]]pack::
+	A set of objects which have been compressed into one file (to save space
+	or to transmit them efficiently).
+
+[[def_pack_index]]pack index::
+	The list of identifiers, and other information, of the objects in a
+	<<def_pack,pack>>, to assist in efficiently accessing the contents of a
+	pack.
+
+[[def_pathspec]]pathspec::
+	Pattern used to limit paths in Git commands.
++
+Pathspecs are used on the command line of "git ls-files", "git
+ls-tree", "git add", "git grep", "git diff", "git checkout",
+and many other commands to
+limit the scope of operations to some subset of the tree or
+worktree.  See the documentation of each command for whether
+paths are relative to the current directory or toplevel.  The
+pathspec syntax is as follows:
++
+--
+
+* any path matches itself
+* the pathspec up to the last slash represents a
+  directory prefix.  The scope of that pathspec is
+  limited to that subtree.
+* the rest of the pathspec is a pattern for the remainder
+  of the pathname.  Paths relative to the directory
+  prefix will be matched against that pattern using fnmatch(3);
+  in particular, '*' and '?' _can_ match directory separators.
+
+--
++
+For example, Documentation/*.jpg will match all .jpg files
+in the Documentation subtree,
+including Documentation/chapter_1/figure_1.jpg.
++
+A pathspec that begins with a colon `:` has special meaning.  In the
+short form, the leading colon `:` is followed by zero or more "magic
+signature" letters (which optionally is terminated by another colon `:`),
+and the remainder is the pattern to match against the path.
+The "magic signature" consists of ASCII symbols that are neither
+alphanumeric, glob, regex special characters nor colon.
+The optional colon that terminates the "magic signature" can be
+omitted if the pattern begins with a character that does not belong to
+"magic signature" symbol set and is not a colon.
++
+In the long form, the leading colon `:` is followed by an open
+parenthesis `(`, a comma-separated list of zero or more "magic words",
+and a close parentheses `)`, and the remainder is the pattern to match
+against the path.
++
+A pathspec with only a colon means "there is no pathspec". This form
+should not be combined with other pathspec.
++
+--
+top;;
+	The magic word `top` (magic signature: `/`) makes the pattern
+	match from the root of the working tree, even when you are
+	running the command from inside a subdirectory.
+
+literal;;
+	Wildcards in the pattern such as `*` or `?` are treated
+	as literal characters.
+
+icase;;
+	Case insensitive match.
+
+glob;;
+	Git treats the pattern as a shell glob suitable for
+	consumption by fnmatch(3) with the FNM_PATHNAME flag:
+	wildcards in the pattern will not match a / in the pathname.
+	For example, "Documentation/{asterisk}.html" matches
+	"Documentation/git.html" but not "Documentation/ppc/ppc.html"
+	or "tools/perf/Documentation/perf.html".
++
+Two consecutive asterisks ("`**`") in patterns matched against
+full pathname may have special meaning:
+
+ - A leading "`**`" followed by a slash means match in all
+   directories. For example, "`**/foo`" matches file or directory
+   "`foo`" anywhere, the same as pattern "`foo`". "`**/foo/bar`"
+   matches file or directory "`bar`" anywhere that is directly
+   under directory "`foo`".
+
+ - A trailing "`/**`" matches everything inside. For example,
+   "`abc/**`" matches all files inside directory "abc", relative
+   to the location of the `.gitignore` file, with infinite depth.
+
+ - A slash followed by two consecutive asterisks then a slash
+   matches zero or more directories. For example, "`a/**/b`"
+   matches "`a/b`", "`a/x/b`", "`a/x/y/b`" and so on.
+
+ - Other consecutive asterisks are considered invalid.
++
+Glob magic is incompatible with literal magic.
+
+attr;;
+After `attr:` comes a space separated list of "attribute
+requirements", all of which must be met in order for the
+path to be considered a match; this is in addition to the
+usual non-magic pathspec pattern matching.
+See linkgit:gitattributes[5].
++
+Each of the attribute requirements for the path takes one of
+these forms:
+
+- "`ATTR`" requires that the attribute `ATTR` be set.
+
+- "`-ATTR`" requires that the attribute `ATTR` be unset.
+
+- "`ATTR=VALUE`" requires that the attribute `ATTR` be
+  set to the string `VALUE`.
+
+- "`!ATTR`" requires that the attribute `ATTR` be
+  unspecified.
++
+Note that when matching against a tree object, attributes are still
+obtained from working tree, not from the given tree object.
+
+exclude;;
+	After a path matches any non-exclude pathspec, it will be run
+	through all exclude pathspecs (magic signature: `!` or its
+	synonym `^`). If it matches, the path is ignored.  When there
+	is no non-exclude pathspec, the exclusion is applied to the
+	result set as if invoked without any pathspec.
+--
+
+[[def_parent]]parent::
+	A <<def_commit_object,commit object>> contains a (possibly empty) list
+	of the logical predecessor(s) in the line of development, i.e. its
+	parents.
+
+[[def_pickaxe]]pickaxe::
+	The term <<def_pickaxe,pickaxe>> refers to an option to the diffcore
+	routines that help select changes that add or delete a given text
+	string. With the `--pickaxe-all` option, it can be used to view the full
+	<<def_changeset,changeset>> that introduced or removed, say, a
+	particular line of text. See linkgit:git-diff[1].
+
+[[def_plumbing]]plumbing::
+	Cute name for <<def_core_git,core Git>>.
+
+[[def_porcelain]]porcelain::
+	Cute name for programs and program suites depending on
+	<<def_core_git,core Git>>, presenting a high level access to
+	core Git. Porcelains expose more of a <<def_SCM,SCM>>
+	interface than the <<def_plumbing,plumbing>>.
+
+[[def_per_worktree_ref]]per-worktree ref::
+	Refs that are per-<<def_working_tree,worktree>>, rather than
+	global.  This is presently only <<def_HEAD,HEAD>> and any refs
+	that start with `refs/bisect/`, but might later include other
+	unusual refs.
+
+[[def_pseudoref]]pseudoref::
+	Pseudorefs are a class of files under `$GIT_DIR` which behave
+	like refs for the purposes of rev-parse, but which are treated
+	specially by git.  Pseudorefs both have names that are all-caps,
+	and always start with a line consisting of a
+	<<def_SHA1,SHA-1>> followed by whitespace.  So, HEAD is not a
+	pseudoref, because it is sometimes a symbolic ref.  They might
+	optionally contain some additional data.  `MERGE_HEAD` and
+	`CHERRY_PICK_HEAD` are examples.  Unlike
+	<<def_per_worktree_ref,per-worktree refs>>, these files cannot
+	be symbolic refs, and never have reflogs.  They also cannot be
+	updated through the normal ref update machinery.  Instead,
+	they are updated by directly writing to the files.  However,
+	they can be read as if they were refs, so `git rev-parse
+	MERGE_HEAD` will work.
+
+[[def_pull]]pull::
+	Pulling a <<def_branch,branch>> means to <<def_fetch,fetch>> it and
+	<<def_merge,merge>> it.  See also linkgit:git-pull[1].
+
+[[def_push]]push::
+	Pushing a <<def_branch,branch>> means to get the branch's
+	<<def_head_ref,head ref>> from a remote <<def_repository,repository>>,
+	find out if it is an ancestor to the branch's local
+	head ref, and in that case, putting all
+	objects, which are <<def_reachable,reachable>> from the local
+	head ref, and which are missing from the remote
+	repository, into the remote
+	<<def_object_database,object database>>, and updating the remote
+	head ref. If the remote <<def_head,head>> is not an
+	ancestor to the local head, the push fails.
+
+[[def_reachable]]reachable::
+	All of the ancestors of a given <<def_commit,commit>> are said to be
+	"reachable" from that commit. More
+	generally, one <<def_object,object>> is reachable from
+	another if we can reach the one from the other by a <<def_chain,chain>>
+	that follows <<def_tag,tags>> to whatever they tag,
+	<<def_commit_object,commits>> to their parents or trees, and
+	<<def_tree_object,trees>> to the trees or <<def_blob_object,blobs>>
+	that they contain.
+
+[[def_rebase]]rebase::
+	To reapply a series of changes from a <<def_branch,branch>> to a
+	different base, and reset the <<def_head,head>> of that branch
+	to the result.
+
+[[def_ref]]ref::
+	A name that begins with `refs/` (e.g. `refs/heads/master`)
+	that points to an <<def_object_name,object name>> or another
+	ref (the latter is called a <<def_symref,symbolic ref>>).
+	For convenience, a ref can sometimes be abbreviated when used
+	as an argument to a Git command; see linkgit:gitrevisions[7]
+	for details.
+	Refs are stored in the <<def_repository,repository>>.
++
+The ref namespace is hierarchical.
+Different subhierarchies are used for different purposes (e.g. the
+`refs/heads/` hierarchy is used to represent local branches).
++
+There are a few special-purpose refs that do not begin with `refs/`.
+The most notable example is `HEAD`.
+
+[[def_reflog]]reflog::
+	A reflog shows the local "history" of a ref.  In other words,
+	it can tell you what the 3rd last revision in _this_ repository
+	was, and what was the current state in _this_ repository,
+	yesterday 9:14pm.  See linkgit:git-reflog[1] for details.
+
+[[def_refspec]]refspec::
+	A "refspec" is used by <<def_fetch,fetch>> and
+	<<def_push,push>> to describe the mapping between remote
+	<<def_ref,ref>> and local ref.
+
+[[def_remote]]remote repository::
+	A <<def_repository,repository>> which is used to track the same
+	project but resides somewhere else. To communicate with remotes,
+	see <<def_fetch,fetch>> or <<def_push,push>>.
+
+[[def_remote_tracking_branch]]remote-tracking branch::
+	A <<def_ref,ref>> that is used to follow changes from another
+	<<def_repository,repository>>. It typically looks like
+	'refs/remotes/foo/bar' (indicating that it tracks a branch named
+	'bar' in a remote named 'foo'), and matches the right-hand-side of
+	a configured fetch <<def_refspec,refspec>>. A remote-tracking
+	branch should not contain direct modifications or have local
+	commits made to it.
+
+[[def_repository]]repository::
+	A collection of <<def_ref,refs>> together with an
+	<<def_object_database,object database>> containing all objects
+	which are <<def_reachable,reachable>> from the refs, possibly
+	accompanied by meta data from one or more <<def_porcelain,porcelains>>. A
+	repository can share an object database with other repositories
+	via <<def_alternate_object_database,alternates mechanism>>.
+
+[[def_resolve]]resolve::
+	The action of fixing up manually what a failed automatic
+	<<def_merge,merge>> left behind.
+
+[[def_revision]]revision::
+	Synonym for <<def_commit,commit>> (the noun).
+
+[[def_rewind]]rewind::
+	To throw away part of the development, i.e. to assign the
+	<<def_head,head>> to an earlier <<def_revision,revision>>.
+
+[[def_SCM]]SCM::
+	Source code management (tool).
+
+[[def_SHA1]]SHA-1::
+	"Secure Hash Algorithm 1"; a cryptographic hash function.
+	In the context of Git used as a synonym for <<def_object_name,object name>>.
+
+[[def_shallow_clone]]shallow clone::
+	Mostly a synonym to <<def_shallow_repository,shallow repository>>
+	but the phrase makes it more explicit that it was created by
+	running `git clone --depth=...` command.
+
+[[def_shallow_repository]]shallow repository::
+	A shallow <<def_repository,repository>> has an incomplete
+	history some of whose <<def_commit,commits>> have <<def_parent,parents>> cauterized away (in other
+	words, Git is told to pretend that these commits do not have the
+	parents, even though they are recorded in the <<def_commit_object,commit
+	object>>). This is sometimes useful when you are interested only in the
+	recent history of a project even though the real history recorded in the
+	upstream is much larger. A shallow repository
+	is created by giving the `--depth` option to linkgit:git-clone[1], and
+	its history can be later deepened with linkgit:git-fetch[1].
+
+[[def_stash]]stash entry::
+	An <<def_object,object>> used to temporarily store the contents of a
+	<<def_dirty,dirty>> working directory and the index for future reuse.
+
+[[def_submodule]]submodule::
+	A <<def_repository,repository>> that holds the history of a
+	separate project inside another repository (the latter of
+	which is called <<def_superproject, superproject>>).
+
+[[def_superproject]]superproject::
+	A <<def_repository,repository>> that references repositories
+	of other projects in its working tree as <<def_submodule,submodules>>.
+	The superproject knows about the names of (but does not hold
+	copies of) commit objects of the contained submodules.
+
+[[def_symref]]symref::
+	Symbolic reference: instead of containing the <<def_SHA1,SHA-1>>
+	id itself, it is of the format 'ref: refs/some/thing' and when
+	referenced, it recursively dereferences to this reference.
+	'<<def_HEAD,HEAD>>' is a prime example of a symref. Symbolic
+	references are manipulated with the linkgit:git-symbolic-ref[1]
+	command.
+
+[[def_tag]]tag::
+	A <<def_ref,ref>> under `refs/tags/` namespace that points to an
+	object of an arbitrary type (typically a tag points to either a
+	<<def_tag_object,tag>> or a <<def_commit_object,commit object>>).
+	In contrast to a <<def_head,head>>, a tag is not updated by
+	the `commit` command. A Git tag has nothing to do with a Lisp
+	tag (which would be called an <<def_object_type,object type>>
+	in Git's context). A tag is most typically used to mark a particular
+	point in the commit ancestry <<def_chain,chain>>.
+
+[[def_tag_object]]tag object::
+	An <<def_object,object>> containing a <<def_ref,ref>> pointing to
+	another object, which can contain a message just like a
+	<<def_commit_object,commit object>>. It can also contain a (PGP)
+	signature, in which case it is called a "signed tag object".
+
+[[def_topic_branch]]topic branch::
+	A regular Git <<def_branch,branch>> that is used by a developer to
+	identify a conceptual line of development. Since branches are very easy
+	and inexpensive, it is often desirable to have several small branches
+	that each contain very well defined concepts or small incremental yet
+	related changes.
+
+[[def_tree]]tree::
+	Either a <<def_working_tree,working tree>>, or a <<def_tree_object,tree
+	object>> together with the dependent <<def_blob_object,blob>> and tree objects
+	(i.e. a stored representation of a working tree).
+
+[[def_tree_object]]tree object::
+	An <<def_object,object>> containing a list of file names and modes along
+	with refs to the associated blob and/or tree objects. A
+	<<def_tree,tree>> is equivalent to a <<def_directory,directory>>.
+
+[[def_tree-ish]]tree-ish (also treeish)::
+	A <<def_tree_object,tree object>> or an <<def_object,object>>
+	that can be recursively dereferenced to a tree object.
+	Dereferencing a <<def_commit_object,commit object>> yields the
+	tree object corresponding to the <<def_revision,revision>>'s
+	top <<def_directory,directory>>.
+	The following are all tree-ishes:
+	a <<def_commit-ish,commit-ish>>,
+	a tree object,
+	a <<def_tag_object,tag object>> that points to a tree object,
+	a tag object that points to a tag object that points to a tree
+	object,
+	etc.
+
+[[def_unmerged_index]]unmerged index::
+	An <<def_index,index>> which contains unmerged
+	<<def_index_entry,index entries>>.
+
+[[def_unreachable_object]]unreachable object::
+	An <<def_object,object>> which is not <<def_reachable,reachable>> from a
+	<<def_branch,branch>>, <<def_tag,tag>>, or any other reference.
+
+[[def_upstream_branch]]upstream branch::
+	The default <<def_branch,branch>> that is merged into the branch in
+	question (or the branch in question is rebased onto). It is configured
+	via branch.<name>.remote and branch.<name>.merge. If the upstream branch
+	of 'A' is 'origin/B' sometimes we say "'A' is tracking 'origin/B'".
+
+[[def_working_tree]]working tree::
+	The tree of actual checked out files.  The working tree normally
+	contains the contents of the <<def_HEAD,HEAD>> commit's tree,
+	plus any local changes that you have made but not yet committed.