From a PLOS Blog Post:

Not all Open Access is created equal. To move beyond the seemingly simple question of Is it Open Access?” PLOS, SPARC and OASPA have collaborated to develop a resource called HowOpenIsIt?” This resource identifies the core components of open access (OA) and how they are implemented across the spectrum between “Open Access” and “Closed Access”. We recognize there are philosophical disagreements regarding OA and this resource will not resolve those differences.

We are seeking input on the accuracy and completeness of how OA is defined in this guide. Download the open review draft and provide feedback via the comment form on the SPARC site.

The goals of the guide are to:
+ Move the conversation from “Is It Open Access?” to “How Open Is It?”
+ Clarify the definition of OA
+ Standardize terminology
+ Illustrate a continuum of “more open” versus “less open”
+ Enable people to compare and contrast publications and policies
+ Broaden the understanding of OA to a wider audience