The PMC Open Access Subset is a relatively small part of the total collection of articles in PMC. Articles in the PMC Open Access Subset are still protected by copyright, but are made available under a Creative Commons or similar license that generally allows more liberal redistribution and reuse than a traditional copyrighted work. Please refer to the license statement in each article for specific terms of use. The license terms are not identical for all articles in this subset.

Note that:

• The majority of the articles in PMC are subject to traditional copyright restrictions and are not part of this subset. Read the PMC Copyright Notice for more information.
  
  
• The PMC OAI service and the PMC FTP service are the only services that may be used for automated downloading of articles from this open access subset.
  
  
• Systematic retrieval (bulk downloading) of articles through any other automated process is prohibited, even if you are only retrieving articles from this subset.
  
  
• Some journals use the label "open access" for an article that is available free at time of publication, but is still subject to traditional copyright restrictions. Such articles are not part of this subset.

The PMC Open Access Subset includes articles from the following publishers' programs, each of which deposits selected articles from a range of journals:

• BMJ Unlocked
• Elsevier Sponsored Documents
• IUCr Open Access
• Oxford Open
• Portland Press Opt2Pay
• Springer Open Choice
• Taylor & Francis iOpenAccess
• Wiley - Blackwell Online Open

In addition to these selective deposit programs, a number of the journals that deposit their complete contents in PMC include some or all their articles in the open access subset. These journals are marked with the symbol   in PMC's Full Journal List.

Use the PMC-OAI service to download XML for the full text of articles in this open access subset.

Use the PMC FTP service to download a complete set of files — XML, images, PDF, and supplementary data files, if any — for articles in this subset. For users who are interested in just the XML, the FTP service also has a single zip file containing the XML files for all the articles in the open access subset.