JESD84-B50 is available for free download from the JEDEC website: here
The new revision of the standard also includes a Field Firmware update procedure which allows loading and installing a new version or a patch of the e.MMC device controller firmware when the device itself is operational in the final system. In addition, Production State Awareness may be used during the production phase, and defines how to inform the device about specific phases such as content pre-loading, soldering, and integration in the final system.
e.MMC v5.0 also proposes some enhancements designed with the end user in mind, including register fields that can be utilized to collect device lifetime statistics via the Device Health Report feature. A safer power mode transition to Sleep state via software is possible through Sleep Notification.