What is the PMC Open Access subset? Isn everything in PMC open access?
The majority of the articles in PMC are subject to traditional copyright restrictions. They are free to access, but they are not Open Access articles in the specialized sense of that term. The PMC Open Access Subset is a relatively small part of the total collection of articles in PMC. Articles in this 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. See the PMC Open Access Subset page for more information on how you may retrieve and use these articles.
