PMC International (PMCI) is a collaborative effort between NLM, the publishers whose journal content makes up the PMC archive, and organizations in other countries that share NLM's interest in archiving life sciences literature. The long term goal of PMCI is to create a network of digital archives that can share some or all of their respective locally deposited content with others in the network. There are several reasons for doing this:

• The probablity of an archive surviving over the long term is greater if there are working copies of the archive in regular use at multiple sites around the world.
• A producer or funder of research literature often will be more inclined to make the primary deposit of its material to a locally or regionally affiliated archive, rather than to one operated elsewhere in the world.
• In areas with limited online communications facilities, users may be better served by a national or regional archive in the vicinity.

The basic principles of this collaboration are that:

• Each PMCI archive is sponsored and managed by a national or international agency. It may be a government agency, or a not-for-profit organization at an equivalent national or international level, formed by non-commercial entities such as universities, research institutions, funding agencies, or professional societies.
• When a publisher signs an agreement to participate in PMC, it gives NLM permission to provide free access to the content it deposits in PMC, and to distribute this content to the PMCI archives. (Publishers who signed PMC participation agreements with NLM prior to the formation of PMC International in July 2006 are invited to enter into a separate agreement with NLM that allows the distribution of their content to the PMCI archives.)
• There is a formal agreement between NLM and each PMCI archive concerning the management of the archive. It is designed to protect publishers' rights to the material they deposit in the archive, ensure the integrity of this content, and ensure that users will always have free access to the content. (See the prototype agreement.)

In the initial phase, each PMCI archive will receive content from the U.S. PMC archive only. At a later stage, an archive may take in some content directly from publishers or other sources and distribute it to other archives in the PMCI network.

Every PMCI archive must use NCBI's portable PMC (pPMC) software to manage, and provide access to, its content. The pPMC system displays articles in the same way as the U.S. PMC system and is similar to it in most respects.

Portable PMC (pPMC)

Portable PMC (pPMC) is a software package being developed by NLM's National Center for Biotechnology Information (NCBI) and currently being tested by several prospective PMCI sites. When complete, it will be available for use by any organization or individual wishing to manage and provide access to a collection of journal articles and related material in a manner similar to that of NLM's PMC system. However, pPMC itself does not include any rights to the PMC content.

The software runs under Microsoft Windows Server® 2000 (or later versions) and requires a local installed copy of Microsoft SQL Server® 2005. NCBI's pPMC package consists of five functional units:

• Data Collector - import content from a distribution service such as one that PMC will provide for approved PMCI archives.
• Database Loader - load data into the pPMC database. Data may come from the collector or from another source that creates it in the same format.
• Renderer - retrieve and display articles as well as issue tables of contents and similar lists.
• Search - full-text searching using services provided by the SQL server. There is also an interface for a locally provided search engine. In addition, a site that has the same content as NLM's PMC system may use the Entrez e-utils web services for searching.
• Administration - monitor system performance and collect usage statistics.

Literature Archiving Software Suite (LASS)

pPMC is part of set of tools being developed by NCBI to support the creation, management and preservation of electronic literature collections and provide access to them. The other components of LASS are:

• NLM XML DTDs - a set of DTDs for journal articles, book chapters and related content.
• NLM XML Authoring Tool - an add-on for Microsoft Word®. It lets one use standard MS Word features to create a properly formatted NLM XML document for a journal article or a book chapter. It provides bi-directional MS Word to NLM XML conversions.
• Portable NIHMS (pNIHMS) - a software package that handles the intake of ‘raw’ manuscripts (word processor or other text files, image files, PDFs, etc.) and tracks them through the process of conversion to an NLM XML format and eventual deposit in an article repository. It is based on the NIH Manuscript Submission (NIHMS) system.

The NLM XML DTDs include an Article Authoring DTD, a Journal Publishing DTD, a Journal Archiving and Interchange DTD and a Book DTD. All are created from the common NLM Archiving and Interchange DTD Suite. They are fully documented and available in the public domain now.

The remaining components of LASS will be made available in the public domain when development has been completed. As public domain products, the LASS packages are free for use by anyone for any purpose. NCBI will maintain them in the sense that it will periodically make updated versions available. There will also be a mail address to which users of the packages may send reports of software failures or suggestions for new features. The LASS packages are provided free and without the routine technical support available for many commercial software products.

Acknowledgements

Microsoft® assisted in the establishment of several PMCI sites. Microsoft assisted in testing NCBI's pPMC software for the purpose of remote deployment. Microsoft verified that the PMCI sites were properly configured and in several cases donated versions of Windows Server and SQL Server. Microsoft installed, tested, and performed troubleshooting at these remote sites and continues to provide technical assistance for software and database updates.