Export
hg export [OPTION]... [-o OUTFILESPEC] REV...
The act of exporting a changeset generates an augmented patch file that describes the change. A Mercurial patch file contains some metadata and a traditional unified diff.
Once a changeset has been exported from one repository, it can be imported into another.
Help text: http://www.cadifra.com/mercurial/hg.1.html#export
See also: CommunicatingChanges, TutorialExport