Abstract: One person/company, that has some service by service provider.
ID - Key field.
account_ID - Foreign key, linking to account table (authorization).
name - Full name of user.
email - User email address, used to send email notifications and other communication.
phone_nr - Phone nr of user. Used for communication and also for sending sms notifications. Number with full international prefix.
checking_enabled - Flag !=0 indicating that system should automatically update this user's service status.
accept_data - Flag !=0 indicating that system should store service instances for this user. If accept_data=0, data about this user uploaded by data provider will not be accepted by system. This is option for very paranoid users ;-)
last_login - Time of last user login. Used to delete users that have not logged in for long time (or not at all).
notify_by_email - Flag !=0 indicating that this user wants to get notifications by email. Overriden by flag in service_instance table, if set there.
notify_by_phone - Flag !=0 indicating that this user wants to get notifications by phone. Overriden by flag in service_instance table, if set there.
comments - Field for administrator AND this user's data suppliers only. Any notes about this user.