# Re: Need OP\_BLOCKNUMBER to allow "time" limited transactions

Post by: satoshi on November 15, 2010, 06:37:44 PM

We can't safely do OP\_BLOCKNUMBER. &nbsp;In the event of a block chain reorg after a segmentation, transactions need to be able to get into the chain in a later block. &nbsp;The OP\_BLOCKNUMBER transaction and all its dependants would become invalid. &nbsp;This wouldn't be fair to later owners of the coins who weren't involved in the time limited transaction.

nTimeLock does the reverse. &nbsp;It's an open transaction that can be replaced with new versions until the deadline. &nbsp;It can't be recorded until it locks. &nbsp;The highest version when the deadline hits gets recorded. &nbsp;It could be used, for example, to write an escrow transaction that will automatically permanently lock and go through unless it is revoked before the deadline. &nbsp;The feature isn't enabled or used yet, but the support is there so it could be implemented later.

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