Based on my reading of CSE spec, there is no section which explains how explicit encryption works on a high level. There are multiple references to explicit encryption throughout the spec, but they appear to be side notes to descriptions of automatic encryption functionality. For a user who only wishes to configure explicit encryption, or for a driver which implements explicit encryption first, it is difficult to:

• Identify what the minimum driver API is to provide explicit encryption feature to the user
• Get a high level idea of how explicit encryption works across all of the components (driver, libmongocrypt, key vault)

It will be helpful to have a dedicated section to explicit encryption which will provide a high level description of the above in prose.