CH12: Median Time Past: move and update

ch10.asciidoc

@@ -1,52 +1,6 @@
 [[mining]]
 == Mining and Consensus
 
-[[mtp]]
-=== Median Time Past (MTP)
-
-((("scripting", "timelocks",
-"Median-Tme-Past")))((("Median-Tme-Past")))((("timelocks",
-"Median-Tme-Past")))As part of the activation of relative timelocks,
-there was also a change in the way "time" is calculated for timelocks
-(both absolute and relative). In bitcoin there is a subtle, but very
-significant, difference between wall time and consensus time. Bitcoin is
-a decentralized network, which means that each participant has his or
-her own perspective of time. Events on the network do not occur
-instantaneously everywhere. Network latency must be factored into the
-perspective of each node. Eventually everything is synchronized to
-create a common ledger. Bitcoin reaches consensus every 10 minutes about
-the state of the ledger as it existed in the _past_.
-
-The timestamps set in block headers are set by the miners. There is a
-certain degree of latitude allowed by the consensus rules to account for
-differences in clock accuracy between decentralized nodes. However, this
-creates an unfortunate incentive for miners to lie about the time in a
-block so as to earn extra fees by including timelocked transactions that
-are not yet mature. See the following section for more information.
-
-To remove the incentive to lie and strengthen the security of timelocks,
-a BIP was proposed and activated at the same time as the BIPs for
-relative timelocks. This is BIP113, which defines a new consensus
-measurement of time called _Median-Time-Past_.
-
-Median-Time-Past is calculated by taking the timestamps of the last 11
-blocks and finding the median. That median time then becomes consensus
-time and is used for all timelock calculations. By taking the midpoint
-from approximately two hours in the past, the influence of any one
-block's timestamp is reduced. By incorporating 11 blocks, no single
-miner can influence the timestamps in order to gain fees from
-transactions with a timelock that hasn't yet matured.
-
-Median-Time-Past changes the implementation of time calculations for
-+nLocktime+, +CLTV+, +nSequence+, and +CSV+. The consensus time
-calculated by Median-Time-Past is always approximately one hour behind
-wall clock time. If you create timelock transactions, you should account
-for it when estimating the desired value to encode in +nLocktime+,
-+nSequence+, +CLTV+, and +CSV+.
-
-Median-Time-Past is specified in
-https://github.com/bitcoin/bips/blob/master/bip-0113.mediawiki[BIP113].
-
 [[duplicate_transactions]]
 === Preventing Duplicate Transactions
 
@@ -1179,6 +1133,60 @@ of electricity in bitcoin, because that determines the profitability of
 mining and therefore the incentives to enter or exit the mining
 market.((("", startref="targets10")))
 
+[[mtp]]
+=== Median Time Past (MTP)
+
+In bitcoin there is a subtle, but very
+significant, difference between wall time and consensus time. Bitcoin is
+a decentralized network, which means that each participant has his or
+her own perspective of time. Events on the network do not occur
+instantaneously everywhere. Network latency must be factored into the
+perspective of each node. Eventually everything is synchronized to
+create a common ledger. Bitcoin reaches consensus every 10 minutes about
+the state of the ledger as it existed in the _past_.
+
+The timestamps set in block headers are set by the miners. There is a
+certain degree of latitude allowed by the consensus rules to account for
+differences in clock accuracy between decentralized nodes. However, this
+creates an unfortunate incentive for miners to lie about the time in a
+block.  For example, if a miner sets their time in the future, they can
+lower difficulty, allowing them to mine more blocks and claim some of
+the block subsidy reserved for future miners.  If they can set their
+times in the past for some blocks, they can use the current time for
+some other blocks, and so again make it look like there's a long time
+between blocks for the purpose of manipulating difficulty.
+
+To prevent manipulation, Bitcoin has two consensus rules.  The first is
+that no node will accept any block with a time further in the future
+than two hours.  The second is that no node will accept a block with a
+time less than or equal to the median time of the last 11 blocks, called
+_median time past_ (MTP).
+
+As part of the activation of BIP68 relative timelocks,
+there was also a change in the way "time" is calculated for timelocks
+(both absolute and relative) in transactions.   Previously, a miner
+could include any transaction in a block with a time lock equal to or
+below the time of the block.  That incentivized miners to use the latest
+possible time they thought was possible (close to two hours in the future)
+so that more transactions would be eligible for their block.
+
+To remove the incentive to lie and strengthen the security of timelocks,
+BIP113 was proposed and activated at the same time as the BIPs for
+relative timelocks.
+The median time past became the consensus
+time and is used for all timelock calculations. By taking the midpoint
+from approximately two hours in the past, the influence of any one
+block's timestamp is reduced. By incorporating 11 blocks, no single
+miner can influence the timestamps in order to gain fees from
+transactions with a timelock that hasn't yet matured.
+
+Median time past changes the implementation of time calculations for
++nLocktime+, +CLTV+, +nSequence+, and +CSV+. The consensus time
+calculated by median time past is usually about one hour behind
+wall clock time. If you create timelock transactions, you should account
+for it when estimating the desired value to encode in +nLocktime+,
++nSequence+, +CLTV+, and +CSV+.
+
 === Successfully Mining the Block
 
 ((("mining and consensus", "mining the block", "successful