Jeff Chan wrote:
The bitmask approach is more compact, but the multiple A record approach is more human-readable and transparent IMO
I don't think human-readability is necessary for an RBL. And the bitmask format is transparent to a program and is more efficient for a program to use. Making it readable to a human could be the task of a query program that is designed to be used by a human. For example, if you have a web page form to query the SURBL it could accept a host or domain name or a URI and display in a list form instead of as a bitmask.
-- sidney