==== BIP 0065 - OP_CHECKLOCKTIMEVERIFY (soft fork)  ====
[[dido:public:ra:xapend:xapend.b_stds:defact:bitcoin:bips| return to the Bitcoin Improvement Proposals ]]

<table>
<caption>Data sheet for OP_CHECKLOCKTIMEVERIFY  </caption>
| Title                      | OP_CHECKLOCKTIMEVERIFY  |
| Layer                      | Consensus (soft fork) |
| Author                     | Peter Todd	 |
| Comments-Summary           | No comments yet. |
| Comments-URI               | [[https://github.com/bitcoin/bips/wiki/Comments:BIP-0065]]    |
| Status                     | Final | 
| Type                       | Standards Track | 
| Created                    | 2014-10-01 |
| Post History               |  |
| Description                | [[https://github.com/bitcoin/bips/blob/master/bip-0065.mediawiki]] |
| License                    | PD |
</table>

  : **Note**: The following is an excerpt from the official [[dido:public:ra:xapend:xapend.a_glossary:b:bitcoin|Bitcoin]] site. It is provided here as a convenience and is not authoritative. Refer to the original document(s) as the authoritative reference.

=== Abstract ===
//This BIP describes a new opcode (OP_CHECKLOCKTIMEVERIFY) for the Bitcoin scripting system that allows a transaction output to be made unspendable until some point in the future.//

=== Summary ===
//CHECKLOCKTIMEVERIFY redefines the existing NOP2 opcode. When executed, if any of the following conditions are true, the script interpreter will terminate with an error://

    * //the stack is empty; or//
    * //the top item on the stack is less than 0; or//
    * //the lock-time type (height vs. timestamp) of the top stack item and the ''nLockTime'' field are not the same; or//
    * //the top stack item is greater than the transaction's ''nLockTime'' field; or//
    * //the nSequence field of the ''txin'' is ''0xffffffff'';//

//Otherwise, script execution will continue as if a NOP had been executed.//

//The nLockTime field in a transaction prevents the transaction from being mined until either a certain [[dido:public:ra:xapend:xapend.a_glossary:b:block_height|block height]], or block time, has been reached. By comparing the [[dido:public:ra:xapend:xapend.a_glossary:a:argument|argument]] to CHECKLOCKTIMEVERIFY against the nLockTime field, we indirectly verify that the desired block height or block time has been reached; until that block height or block time has been reached the transaction output remains unspendable//