diff --git a/ch07.asciidoc b/ch07.asciidoc index 801fb848..e58a977b 100644 --- a/ch07.asciidoc +++ b/ch07.asciidoc @@ -221,7 +221,7 @@ RETURN was initially proposed with a limit of 80 bytes, but the limit was reduce === Timelocks -Timelocks are restrictions on transactions or outputs that only allow spending after a point in time. Bitcoin has had a transaction-level timelock feature from the beginning. It is implemented by the nLocktime filed in a transaction. Two new timelock features were introduced in late 2015 and mid-2016 that offer UTXO-level timelocks. These are +CHECKLOCKTIMEVERIFY+, and CHECKSEQUENCEVERIFY. +Timelocks are restrictions on transactions or outputs that only allow spending after a point in time. Bitcoin has had a transaction-level timelock feature from the beginning. It is implemented by the nLocktime field in a transaction. Two new timelock features were introduced in late 2015 and mid-2016 that offer UTXO-level timelocks. These are +CHECKLOCKTIMEVERIFY+, and CHECKSEQUENCEVERIFY. Timelocks are useful for post-dating transactions and locking funds to a date in the future. More importantly, timelocks extend bitcoin scripting into the dimension of time, opening the door for complex multi-step smart contracts. We will examine the use of timelocks for smart contracts in <>. @@ -309,7 +309,7 @@ nLocktime and CLTV are both _absolute timelocks_ in that the specify an absolute Relative timelocks are useful because they allow a chain of two or more interdependent transactions to be held off chain, while imposing a time constraint on one transaction that is dependent on the elapsed time from the confirmation of a previous transaction. In other words, the clock doesn't start counting until the UTXO is recorded on the blockchain. This functionality is especially useful in bi-directional state channels and Lightning network, as we will see in <>. -Relative timelocks, like absolute timelocks are implemented with both a transaction-level feature and a script-level opcode. The transaction-level relative timelock is implemented as a consensus rule on the value of nSequence, a transaction field which is set in every transaction input. Script-level relative timelocks are implemented with the CHECKSEQUENCEVERIFY opcode. +Relative timelocks, like absolute timelocks, are implemented with both a transaction-level feature and a script-level opcode. The transaction-level relative timelock is implemented as a consensus rule on the value of nSequence, a transaction field which is set in every transaction input. Script-level relative timelocks are implemented with the CHECKSEQUENCEVERIFY opcode. Relative timelocks are implemented according to the specifications in the following BIPs: