INIT_SS_ADMIN in docker .env configuration

In the .env configuration file, I understand this is the initial admin user for logon to web:

### Seafile admin user
INIT_SEAFILE_ADMIN_EMAIL=rob@robnicholson.me.uk
INIT_SEAFILE_ADMIN_PASSWORD=PASSWORD

However, what is this used for?

## Initial variables (can be removed after firstime startup SeaSearch service)
INIT_SS_ADMIN_USER=rob.nicholson
INIT_SS_ADMIN_PASSWORD=PASSWORD

They’re not documented on this page: Setup pro edition - Seafile Admin Manual