>>605
From what I can tell, a node can only broadcast that they are interested in a particular version of the board. You can request a hash, but a hash is associated with only one version of one file (given there are no collisions) in the network. Any modification of that file would no longer have the same hash. The file would have no way of predicting what the next hash would be, since the hash is determined by the content, which supposedly it wouldn't know at least in the case of a BBS. I'm still learning about this, so I could be completely wrong.