tag:
priority: 300
type: txt
help: Loopback interface name
syntax:expression: pattern $VAR(@) "^lo$" ; "name must be lo"
val_help: lo: Loopback interface name

syntax:expression: exec \
   "/opt/vyatta/sbin/vyatta-interfaces.pl --dev=$VAR(@) --check=loopback"
allowed: /opt/vyatta/sbin/vyatta-interfaces.pl --show=loopback
create: ip link set $VAR(@) up