There’s an updated (April 2020) Dynamics 365 Business Central Licensing Guide.
The main change is the inclusion of the Sales and Customer Service Professional Attach licences that may be acquired and assigned to either Business Central Essentials or Premium users. Find this detailed on pages 2 and 13. As usual there’s a full Change Log on page 14.
Find this updated guide here: https://bit.ly/D365BCLGApr2020