The /etc/ppp/pppoe.device file describes the services that are offered on one interface of a PPPoE access server. /etc/ppp/pppoe.device also includes options that define how PPP runs over the PPPoE tunnel. /etc/ppp/pppoe.device is an optional file, which operates exactly like the global /etc/ppp/pppoe. However, if /etc/ppp/pppoe.device is defined for an interface, its parameters have precedence for that interface over the global parameters that are defined in /etc/ppp/pppoe.
service service-name service-specific-options service another-service-name service-specific-options
The only difference between this syntax and the syntax of /etc/ppp/pppoe is that you cannot use the device option that is shown in /etc/ppp/pppoe File.