.. _PMR-introduction:

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PMR - an introduction
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The Physiome Model Repository, :abbr:`PMR (Physiome Model Repository)`, includes the CellML and FieldML repositories, and is powered by software called PMR2. PMR relies on the distributed version control system Mercurial (Hg), which allows the repository to maintain a complete history of all changes made to every file contained within repository :term:`workspaces`. In order to use the Physiome Model Repository, you will need to obtain a Mercurial client for your operating system, and become familiar with the basic functions of Mercurial. There are many excellent resources available on the internet, such as `Mercurial, the definitive guide <http://hgbook.red-bean.com/read/>`_. Mercurial clients may be downloaded from the `Mercurial website <http://mercurial.selenic.com/>`_, which also provides documentation on Mercurial usage. A graphical alternative to a command-line client is available for Windows, called `TortoiseHg <http://tortoisehg.bitbucket.org/>`_. This provides a Windows explorer integrated system for working with Mercurial repositories.