Any changeset that can be reached by an unbroken chain of parent
        changesets from a given changeset. More precisely, the ancestors
        of a changeset can be defined by two properties: a parent of a
        changeset is an ancestor, and a parent of an ancestor is an
        ancestor. See also: 'Descendant'.
        Bookmarks are pointers to certain commits that move when
        committing. They are similar to tags in that it is possible to use
        bookmark names in all places where Mercurial expects a changeset
        ID, e.g., with :hg:`update`. Unlike tags, bookmarks move along
        when you make a commit.
        Bookmarks can be renamed, copied and deleted. Bookmarks are local,
        unless they are explicitly pushed or pulled between repositories.
        Pushing and pulling bookmarks allow you to collaborate with others
        on a branch without creating a named branch.
        (Noun) A child changeset that has been created from a parent that
        is not a head. These are known as topological branches, see
        'Branch, topological'. If a topological branch is named, it becomes
        a named branch. If a topological branch is not named, it becomes
        an anonymous branch. See 'Branch, anonymous' and 'Branch, named'.
        Branches may be created when changes are pulled from or pushed to
        a remote repository, since new heads may be created by these
        operations. Note that the term branch can also be used informally
        to describe a development process in which certain development is
        done independently of other development. This is sometimes done
        explicitly with a named branch, but it can also be done locally,
        using bookmarks or clones and anonymous branches.
        Example: "The experimental branch".
        (Verb) The action of creating a child changeset which results in
        its parent having more than one child.
        Example: "I'm going to branch at X".
    Branch, anonymous
        Every time a new child changeset is created from a parent that is not
        a head and the name of the branch is not changed, a new anonymous
        branch is created.
    Branch, closed
        A named branch whose branch heads have all been closed.
    Branch, default
        The branch assigned to a changeset when no name has previously been
    Branch head
        See 'Head, branch'.
    Branch, inactive
        If a named branch has no topological heads, it is considered to be
        inactive. As an example, a feature branch becomes inactive when it
        is merged into the default branch. The :hg:`branches` command
        shows inactive branches by default, though they can be hidden with
        :hg:`branches --active`.
        NOTE: this concept is deprecated because it is too implicit.
        Branches should now be explicitly closed using :hg:`commit
        --close-branch` when they are no longer needed.
    Branch, named
        A collection of changesets which have the same branch name. By
        default, children of a changeset in a named branch belong to the
        same named branch. A child can be explicitly assigned to a
        different branch. See :hg:`help branch`, :hg:`help branches` and
        :hg:`commit --close-branch` for more information on managing
        Named branches can be thought of as a kind of namespace, dividing
        the collection of changesets that comprise the repository into a
        collection of disjoint subsets. A named branch is not necessarily
        a topological branch. If a new named branch is created from the
        head of another named branch, or the default branch, but no
        further changesets are added to that previous branch, then that
        previous branch will be a branch in name only.
    Branch tip
        See 'Tip, branch'.
    Branch, topological
        Every time a new child changeset is created from a parent that is
        not a head, a new topological branch is created. If a topological
        branch is named, it becomes a named branch. If a topological
        branch is not named, it becomes an anonymous branch of the
        current, possibly default, branch.
        A record of the changesets in the order in which they were added
        to the repository. This includes details such as changeset id,
        author, commit message, date, and list of changed files.
        A snapshot of the state of the repository used to record a change.
    Changeset, child
        The converse of parent changeset: if P is a parent of C, then C is
        a child of P. There is no limit to the number of children that a
        changeset may have.
    Changeset id
        A SHA-1 hash that uniquely identifies a changeset. It may be
        represented as either a "long" 40 hexadecimal digit string, or a
        "short" 12 hexadecimal digit string.
    Changeset, merge
        A changeset with two parents. This occurs when a merge is
    Changeset, parent
        A revision upon which a child changeset is based. Specifically, a
        parent changeset of a changeset C is a changeset whose node
        immediately precedes C in the DAG. Changesets have at most two
        (Noun) The working directory being updated to a specific
        revision. This use should probably be avoided where possible, as
        changeset is much more appropriate than checkout in this context.
        Example: "I'm using checkout X."
        (Verb) Updating the working directory to a specific changeset. See
        :hg:`help update`.
        Example: "I'm going to check out changeset X."
    Child changeset
        See 'Changeset, child'.
    Close changeset
        See 'Head, closed branch'
    Closed branch
        See 'Branch, closed'.
        (Noun) An entire or partial copy of a repository. The partial
        clone must be in the form of a revision and its ancestors.
        Example: "Is your clone up to date?".
        (Verb) The process of creating a clone, using :hg:`clone`.
        Example: "I'm going to clone the repository".
    Closed branch head
        See 'Head, closed branch'.
        (Noun) A synonym for changeset.
        Example: "Is the bug fixed in your recent commit?"
        (Verb) The act of recording changes to a repository. When files
        are committed in a working directory, Mercurial finds the
        differences between the committed files and their parent
        changeset, creating a new changeset in the repository.
        Example: "You should commit those changes now."
        A common abbreviation of the term changeset.
        The repository of changesets of a distributed version control
        system (DVCS) can be described as a directed acyclic graph (DAG),
        consisting of nodes and edges, where nodes correspond to
        changesets and edges imply a parent -> child relation. This graph
        can be visualized by graphical tools such as :hg:`log --graph`. In
        Mercurial, the DAG is limited by the requirement for children to
        have at most two parents.
    Default branch
        See 'Branch, default'.
        Any changeset that can be reached by a chain of child changesets
        from a given changeset. More precisely, the descendants of a
        changeset can be defined by two properties: the child of a
        changeset is a descendant, and the child of a descendant is a
        descendant. See also: 'Ancestor'.
        (Noun) The difference between the contents and attributes of files
        in two changesets or a changeset and the current working
        directory. The difference is usually represented in a standard
        form called a "diff" or "patch". The "git diff" format is used
        when the changes include copies, renames, or changes to file
        attributes, none of which can be represented/handled by classic
        "diff" and "patch".
        Example: "Did you see my correction in the diff?"
        (Verb) Diffing two changesets is the action of creating a diff or
        Example: "If you diff with changeset X, you will see what I mean."
    Directory, working
        The working directory represents the state of the files tracked by
        Mercurial, that will be recorded in the next commit. The working
        directory initially corresponds to the snapshot at an existing
        changeset, known as the parent of the working directory. See
        'Parent, working directory'. The state may be modified by changes
        to the files introduced manually or by a merge. The repository
        metadata exists in the .hg directory inside the working directory.
        Changesets in the draft phase have not been shared with publishing
        repositories and may thus be safely changed by history-modifying
        extensions. See :hg:`help phases`.
        See DAG and :hg:`log --graph`.
        The term 'head' may be used to refer to both a branch head or a
        repository head, depending on the context. See 'Head, branch' and
        'Head, repository' for specific definitions.
        Heads are where development generally takes place and are the
        usual targets for update and merge operations.
    Head, branch
        A changeset with no descendants on the same named branch.
    Head, closed branch
        A changeset that marks a head as no longer interesting. The closed
        head is no longer listed by :hg:`heads`. A branch is considered
        closed when all its heads are closed and consequently is not
        listed by :hg:`branches`.
        Closed heads can be re-opened by committing new changeset as the
        child of the changeset that marks a head as closed.
    Head, repository
        A topological head which has not been closed.
    Head, topological
        A changeset with no children in the repository.
    History, immutable
        Once committed, changesets cannot be altered.  Extensions which
        appear to change history actually create new changesets that
        replace existing ones, and then destroy the old changesets. Doing
        so in public repositories can result in old changesets being
        reintroduced to the repository.
    History, rewriting
        The changesets in a repository are immutable. However, extensions
        to Mercurial can be used to alter the repository, usually in such
        a way as to preserve changeset contents.
    Immutable history
        See 'History, immutable'.
    Merge changeset
        See 'Changeset, merge'.
        Each changeset has a manifest, which is the list of files that are
        tracked by the changeset.
        Used to bring together divergent branches of work. When you update
        to a changeset and then merge another changeset, you bring the
        history of the latter changeset into your working directory. Once
        conflicts are resolved (and marked), this merge may be committed
        as a merge changeset, bringing two branches together in the DAG.
    Named branch
        See 'Branch, named'.
    Null changeset
        The empty changeset. It is the parent state of newly-initialized
        repositories and repositories with no checked out revision. It is
        thus the parent of root changesets and the effective ancestor when
        merging unrelated changesets. Can be specified by the alias 'null'
        or by the changeset ID '000000000000'.
        See 'Changeset, parent'.
    Parent changeset
        See 'Changeset, parent'.
    Parent, working directory
        The working directory parent reflects a virtual revision which is
        the child of the changeset (or two changesets with an uncommitted
        merge) shown by :hg:`parents`. This is changed with
        :hg:`update`. Other commands to see the working directory parent
        are :hg:`summary` and :hg:`id`. Can be specified by the alias ".".
        (Noun) The product of a diff operation.
        Example: "I've sent you my patch."
        (Verb) The process of using a patch file to transform one
        changeset into another.
        Example: "You will need to patch that revision."
        A per-changeset state tracking how the changeset has been or
        should be shared. See :hg:`help phases`.
        Changesets in the public phase have been shared with publishing
        repositories and are therefore considered immutable. See :hg:`help
        An operation in which changesets in a remote repository which are
        not in the local repository are brought into the local
        repository. Note that this operation without special arguments
        only updates the repository, it does not update the files in the
        working directory. See :hg:`help pull`.
        An operation in which changesets in a local repository which are
        not in a remote repository are sent to the remote repository. Note
        that this operation only adds changesets which have been committed
        locally to the remote repository. Uncommitted changes are not
        sent. See :hg:`help push`.
        The metadata describing all recorded states of a collection of
        files. Each recorded state is represented by a changeset. A
        repository is usually (but not always) found in the ``.hg``
        subdirectory of a working directory. Any recorded state can be
        recreated by "updating" a working directory to a specific
    Repository head
        See 'Head, repository'.
        A state of the repository at some point in time. Earlier revisions
        can be updated to by using :hg:`update`.  See also 'Revision
        number'; See also 'Changeset'.
    Revision number
        This integer uniquely identifies a changeset in a specific
        repository. It represents the order in which changesets were added
        to a repository, starting with revision number 0. Note that the
        revision number may be different in each clone of a repository. To
        identify changesets uniquely between different clones, see
        'Changeset id'.
        History storage mechanism used by Mercurial. It is a form of delta
        encoding, with occasional full revision of data followed by delta
        of each successive revision. It includes data and an index
        pointing to the data.
    Rewriting history
        See 'History, rewriting'.
        A changeset that has only the null changeset as its parent. Most
        repositories have only a single root changeset.
        Changesets in the secret phase may not be shared via push, pull,
        or clone. See :hg:`help phases`.
        An alternative name given to a changeset. Tags can be used in all
        places where Mercurial expects a changeset ID, e.g., with
        :hg:`update`. The creation of a tag is stored in the history and
        will thus automatically be shared with other using push and pull.
        The changeset with the highest revision number. It is the changeset
        most recently added in a repository.
    Tip, branch
        The head of a given branch with the highest revision number. When
        a branch name is used as a revision identifier, it refers to the
        branch tip. See also 'Branch, head'. Note that because revision
        numbers may be different in different repository clones, the
        branch tip may be different in different cloned repositories.
        (Noun) Another synonym of changeset.
        Example: "I've pushed an update".
        (Verb) This term is usually used to describe updating the state of
        the working directory to that of a specific changeset. See
        :hg:`help update`.
        Example: "You should update".
    Working directory
        See 'Directory, working'.
    Working directory parent
        See 'Parent, working directory'.