How will it be in transaction script?
This is from the white-paper, due to be released soon:
Section 8.4.2. Final Transactions
When a transaction is sent out to the network, if it is accepted by nodes as valid, the user then has no power to reverse it. The needs for a reversal would come into view when a user accidentally sends to the wrong address. In this case, the coins would be lost with most digital currencies, but for the case of Coin Shield, there will be an option to send the transaction as reversible. What this means as far as informational processing, is that the transaction will be sent out and accepted into a holding structure. It will remain in this holding until the given expiration time has been reached. This will give the user who sent transaction power to cancel the transaction by one’s node verifying ownership of the inputs, and then sending a transaction void to the network. This will remove the transaction from the holding structure, preventing it from being confirmed by the network. In this, the inputs will not be spent by this node’s wallet, so therefore the coins will not be debited from one’s account. If the expiration time is reached, and a transaction void is not sent out by this time, the transaction will then move to the main holding structure termed: memory pool. This will hold the transaction until the miners include it in a new block, therefore confirming it by the network.
I am assuming this "holding structure" would be a master-node on the network or centralized escrow service of some type, but Videlicet will have to give us a glimpse into his vision
No sir, correlate the colors, a secondary memory pool which would be on every node choosing to take part in relaying transactions to allow it to remain decentralized. These will be core nodes that will build trust with one another, agree on checkpoints and blocks, and act to give the outer layers of the network transaction confirmations, ect. so these outer nodes don't have to host the chain themselves or sync. Useful for mobile wallets, personal wallets, etc.
Thank You,
Viz.