Hello!
I have a problem, configuring my router, running on ROS V3.18
When I try to add any rule into prefix list (OSPF is configured properly and now i want to filter out some prefixes from the ospf-output), router returns me an error “Couldn’t add New Prefix List Rule - This feature is not available (6)”.
Does it mean, that I don’t have proper license or may be in v3.18 this feature does not work at all? or may be I’m doing something wrong?!.. 
Prefix list should be used only to filter RIP routes.
for OSPF use routing-filters instead. To filter incoming routes add rules to ospf-in chain, to filter outgoing - use ospf-out chain.
Thank you, routing filters working fine!