What is ROON_ID_DIR/.rmembid used for?

I recognised, when changing or setting the ROON_ID_DIR environment variable for the Roon Server process, all apps need to login again and sometimes unauthorize the previously authrorized server instance. All that I can find in the set directory is a file named .rmembid which contains a kind of UUID (not matching the $ROON_DATAROOT/RAATServer/Settings/unique_id). But when ROON_ID_DIR is not set, such file is not created anywhere on the system, but I do not recognise any issues and also restarting the server and such do not make the apps loose connection or require to login again.

So the questions are what this variable/file is used for, where the info is stored when this variable is not set, and whether it is possible to set the variable without loosing apps authorization states, e.g. by manually pre-creating this file based on a UUID extracted from elsewhere?

Does nobody know :grinning_face_with_smiling_eyes: ? As of another rework of Roon Server (to run as non-root user), the question came up again. Since when changing the servers service user implies a re-authentication/login and unauthorization of the server in the app anyway, ROON_ID_DIR can now be added, but still wondering what it is used for.