Discussions about open access (OA) have been going on for almost two decades. Under pressure from the OA movement, libraries and publishers started to renegotiate journal agreements with an emphasis on transparency and affordability. Library consortia and libraries demand OA parameters in agreements. On the other hand, publishers also make efforts to find a sustainable way to operate the business in the face of significant changes in scholarly communication. New pricing and agreement models have been developed and "transformative agreements" can be an umbrella term for them. Transformative agreements shift the focus of scholarly journal licensing from a subscription model to an OA publishing fee. New types of contract have resulted in major changes in how library budgets are allocated. In this paper, we review the literature to identify the basic principles of contracts and to summarize OA parameters by studying existing transformative agreements, including those agreements Iowa State University signed with Oxford University Press, Cambridge University Press, and the Association for Computing Machinery. It is hoped that libraries can have a better understanding of the direction of travel in future negotiations, and provide libraries with suggestions on how to negotiate OA agreements.