The annual IDPF Digital Book conference took place this week in New York, as part of the BookExpo America trade show for the publishing industry. You can count on two topics being discussed at book publishing conference: Amazon and DRM. IDPF Digital Book 2015 was no exception. One particular panel featured writers from leading book industry trade magazines, and the moderator was Joe Wikert, a respected digital publishing executive who is an outspoken opponent of DRM. The discussion turned to the pros and cons of “walled gardens” such as Amazon’s Kindle ecosystem. Wikert remarked on how quickly the music industry got rid of DRM and suggested — as he often does — that the major trade book publishers should follow.