> "In a bitcoin context, it is also subject to definition" Emphasis on **also**. You still are providing examples, not authoritative definition because if we could code sth like this exactly, we would already have done it and made it consensus. > "One need not have a 100% effectiveness rate for the filters to be useful." I agree. That is why there are protections in bitcoin against many types of attacks against real DoS vectors. Op_returns don't present such a threat. If they did, miners did not have an incentive to mine them because their nodes would crash and mining operations would be disrupted. They are valid transactions you (and I for the matter) don't agree with but the economical incentive says it is profitable to mine them, and it causes a less far-reaching impact than doing such things in other ways. A filter that disrupts economic activity and has worse impacts than dropping it, is harmful overall. Users can make whimsical choices and think they will virtue signal with filters but I estimate this is not going to be enough when facing economic reality, especially in the long run.