The file format is currently a simple text file with an option per line.
user
password
hostname
update url
update delay
log mode
update also on local IP change
You should use the gui to edit all settings and, if possible, avoid editing the file directly.
All options are mandatory.
The file format might change in future versions.
User: username
Password: password
Hostname: hostname
Update url: must be only the domain (sub domain included if necesary), the full update url will be: https://updateurl?hostname=hostname as you can see in gui.
Update delay: a number expressed in minutes between 1min and 24h (greater values are truncated to the max allowed)
Log mode: one of the following strings are allowed: noLog, logHere, logTemp.
Update also on local IP change: one of the following strings are allowed: True, False