Bundlers with at least one non-filtered rule advertise to other peers the minimum rate among their non-filtered rules. This is the minimum rate at which the bundler will accept child transactions without checking any other property except the fee. The bundler signs such rates announcements with the private key of the bundler's account. To prevent fake rates announcements, they can be filtered based on this account effective balance (default set in nxt.minBundlerBalanceFXT is 1000 ARDR). Bundlers that have at least one filter added to all of their rules are considered private and their rates are not announced.