### types of private order flows

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<img width="759" src="https://user-images.githubusercontent.com/1130416/217937850-9b7e9434-ee72-4c2a-9e5e-ae9fe795310e.png">

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#### rpc-based "payment for order flow protocols" (POFPs)

* this type of private order flows can be realized by modifying either the user's rpc or by modifying the protocol's frontend
* the rpc endpoint re-broadcasts (forwarding) the tx to nodes. 
* in respect to every pending tx they receive, they can: 1) censor, 2) forward to some mempool, or 3) forward it directly to some block-builders or validators.

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#### validator transaction reordering protocols (VTRPs)



* private tx reordering
* two goals: 1) identify valuable user txs, 2) replace the POFP's value-extracted tx with its own value-extractive tx
* when a VTRP is able to identify a valuable user tx but, due to the tactics of the POFP, is unable to inject its own transaction in place of the POFP's -> VTRP's optimal strategy is to censor the user's transaction from the final block

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