Hi Guillaume Goulet-Vallieres,
Thanks for pointing it out I just reported the same internally for correction in the documentation as well as towards implementation.
It looks like there is an overall restructuring happening on REST API's where we are moving from old structure where everything is accessible via /datamanagement/a/api/<versionId>/users whereas with 6.6 I can see proper structuring where administrative actions are separated under /administration/v5/servers.
However there are still lot of general API's which follows the same old pattern for example /datamanagement/a/api/v5/applications?only_active=true which can be rewritten aligned to new structure i.e. /datamanagement/ra/api/v5/applications?only_active=true and yield same results.
To my understanding what I observe it looks like ra & a are symbolically representing same Tree node beneath which API's are exposed.
However, I am not sure if this is left for some backward compatibility or some mistake but I have reported the same internally and have requested for more clarification.
From what it looks to me is an interim stage left for comfy of old users.
However, as you pointed I believe it should be aligned properly and should be covered in document.
Regards,
Saurabh