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Revision as of 11:47, 23 September 2019 by Darosior (talk | contribs) (Updated the page to reflect the actual consensus meaning of the `nLockTime` field.)
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nLockTime is a parameter of a transaction, that, if any input indicates so (by having nSequence not equal to UINT_MAX), mandates a minimal time (specified in either unix time or block height), before which the transaction cannot be accepted into a block. If all inputs in a transaction have nSequence equal to UINT_MAX, then nLockTime is ignored.

Since BIP68, a new meaning has been given to the nLockTime and nSequence fields. Given a transaction,

  • If the most significant bit (1<<31) is set
    • If the 23rd bit (1<<22) is set
      • Specifies a time in units of 512 seconds. The transaction can only be included in a block if block_time > nLockTime * 512.
    • Otherwise
      • Specifies a block height before which the transaction can not be included in a block.
  • Otherwise
    • the transaction can be included in any block

See Also