There are three essential types of access to this content, which we will call access levels. We argue that these access levels must be supported by services in order to create an environment in which OA content can be fully exploited. They are: -Access at the granularity of papers. -Analytical access at the granularity of collections. -Access to raw data

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While developers are interested in accessing the raw data, for example through an API, academics will primarily require accessing the content at the level of individual items or relatively small sets of items, mostly expecting to communicate with a digital library (DL) using a set of search and exploration tools. A relatively specific group of users are eResearchers3 whose work is largely motivated by information communicated at the transaction and analytical levels, but in terms of their actual work are mostly dependent on raw data access typically realised using APIs and downloadable datasets.