What is the difference?
config interface 'modem'
option type 'bridge'
option ifname 'eth3 eth4 eth5 ptm0'
and
config interface 'modem'
option type 'bridge'
list ifname 'eth0'
list ifname 'eth1'
list ifname 'eth2'
list ifname 'eth3'
list ifname 'eth5'
list ifname 'ptm0'