Autnum class
New attributes: mp-import/mp-export
mp-import : afi ipv6.unicast,ipv4 from AS1 action pref = 1; accept as-foo;
except { afi ipv6.unicast,ipv4
from AS2 action pref = 2; accept AS226;
except { afi ipv6.unicast
from AS3 action pref = 3; accept {3FFE:FFFF::/35};