A successful fungible token send has two state transitions depending if the transfer is a movement forward or backwards in the token’s timeline:
Sender chain is the source chain, i.e a transfer to any chain other than the one it was previously received from is a movement forwards in the token’s timeline. This results in the following state transitions:
The coins are transferred to an escrow address (i.e locked) on the sender chain.
The coins are transferred to the receiving chain through IBC TAO logic.
Sender chain is the sink chain, i.e the token is sent back to the chain it previously received from. This is a backwards movement in the token’s timeline. This results in the following state transitions:
The coins (vouchers) are burned on the sender chain.
The coins are transferred to the receiving chain through IBC TAO logic.