Runtime parameters for a systemd service

I am a little confused about how runtime parameters are normally supplied to a systemd service. The general idea I have is that the following happens: There is a file that contains the environment variable settings, e.g., /etc/sysconfig/mydaemon Then there is the unit file, e.g., mydaemon.service (not sure where this is located) Inside of the unit file is a line such as the following: EnvironmentFile=-/etc/sysconfig/mydaemon When the service is started, the settings file is opened then each setting is supplied to main as argc/argv. Is that right?