To support non-trivial clients, such as data exploration and analysis environments, digital libraries must be able to describe the access modes that their contents support. We present a simple scheme that distinguishes four content accessibility classes: download (byte-stream retrieval), service (API), web interface (interactive), and offline. These access modes may recursively nest in alternative (semantically equivalent) or multipart (component) hierarchies. This scheme is simple enough to be easily supported by DL content providers, yet rich enough to allow programmatic clients to automatically identify appropriate access point(s).