From the white paper, page 5:
We construct an interactive game whereby the exiting party attests to a bitmap of participants’ ledger outputs arranged in an UTXO model which requests a withdrawal.
Are these bitmaps matrixes of bits, just like in images? Or key-value pairs? Then, given the underlying economic incentives of Plasma, who stores them and how? Is there a model similar to Bitcon's UTXO storage, i.e.