This is likely a system that uploads text to the blockchain.
One example can be seen on the marijuana plant.
Messages are uploaded one line per transaction, and thus may be cut up on the blk.txt, and possibly even out of order.
But because each line starts with
j(you can generally piece things up regardless.
TODO identify. The first occurrence seems to be in tx e8c61e29c6b829e289f8d0fc95f9eb2eb00c89c85cfa3a9c700b15805451ae6a: