CH02: edits for Mark (Xekyo) Erhardt feedback (thanks!)

- Drop unnecessary mentions of people from CH01

- FIXMEs: add notes for image corrections and best blockchain change

- Drop unnecessary mention of debits and credits

- Remove mention about asking block explorer for UTXOs to construct a
  transaction.  This is unnecessary detail and it can never entirely
  work for our example if we later use it to spend the output (because
  then the output won't be unspent)

- Instead of "new block" use "candidate block"

- Drop unnecessary mention of payment consolidation.  We already
  adequetely introduce this concept earlier in the chapter.

ch02.asciidoc

@@ -24,7 +24,7 @@ which is the authoritative ledger of all transactions.
 
 ((("blockchain explorer sites")))Each example in this chapter is based
 on an actual transaction made on the Bitcoin network, simulating the
-interactions between the users (Joe, Alice, Bob, and Gopesh) by sending
+interactions between several users by sending
 funds from one wallet to another. While tracking a transaction through
 the Bitcoin network to the blockchain, we will use a _blockchain
 explorer_ site to visualize each step. A blockchain explorer is a web
@@ -32,6 +32,7 @@ application that operates as a bitcoin search engine, in that it allows
 you to search for addresses, transactions, and blocks and see the
 relationships and flows between them.
 
+//FIXME: priv key to P2PKH address
 [[bitcoin-overview]]
 .Bitcoin overview
 image::images/mbc2_0201.png["Bitcoin Overview"]
@@ -171,10 +172,10 @@ owner, and so on, in a chain of ownership.
 ((("transactions", "overview of", id="Tover02")))((("outputs and
 inputs", "basics of")))Transactions are like lines in a double-entry
 bookkeeping ledger.  Each transaction contains one or more "inputs,"
-which are like debits against a bitcoin account. On the other side of
+which spend funds. On the other side of
-the transaction, there are one or more "outputs," which are like credits
+the transaction, there are one or more "outputs," which receive funds.
-added to a bitcoin account. ((("fees", "transaction fees")))The inputs
+((("fees", "transaction fees")))The inputs
-and outputs (debits and credits) do not necessarily add up to the same
+and outputs do not necessarily add up to the same
 amount. Instead, outputs add up to slightly less than inputs and the
 difference represents an implied _transaction fee_, which is a small
 payment collected by the miner who includes the transaction in the
@@ -234,6 +235,8 @@ change.
 @enddittaa
 ////
 
+//FIXME: clarify that these aren't the same transactions as described in
+//the text
 [[transaction-chain]]
 .A chain of transactions, where the output of one transaction is the input of the next transaction
 image::images/transaction-chain.png["Transaction chain"]
@@ -257,7 +260,7 @@ addresses")))In addition to one or more outputs that pay the receiver of
 bitcoins, many transactions will also include an output that pays the
 spender of the bitcoins, called a _change_ output.
 This is because transaction inputs,
-like currency notes, cannot be divided. If you purchase a $5 US dollar
+like currency notes, cannot be partly spent. If you purchase a $5 US dollar
 item in a store but use a $20 dollar bill to pay for the item, you
 expect to receive $15 dollars in change. The same concept applies to
 bitcoin transaction inputs. If you purchased an item that costs 5
@@ -308,7 +311,7 @@ Another common form of transaction is a _consolidation transaction_ one that spe
 into a single output (<<transaction-consolidating>>). This represents
 the real-world equivalent of exchanging a pile of coins and currency
 notes for a single larger note. Transactions like these are sometimes
-generated by wallets and business to clean up lots of smaller amounts.
+generated by wallets and businesses to clean up lots of smaller amounts.
 
 [[transaction-consolidating]]
 .Transaction aggregating funds
@@ -354,62 +357,6 @@ However, because full nodes use more resources, most
 user wallets run "lightweight" clients that track only the user's own
 UTXOs.
 
-If the wallet application does not maintain a copy of all UTXOs, it can
-query the Bitcoin network to retrieve this
-information using a variety of APIs available by different providers or
-by asking a full node using an application programming interface (API)
-call. <<example_2-2>> shows an API request, constructed as an HTTP GET
-command to a specific URL. This URL will return all the unspent
-transaction outputs for an address, giving any application the
-information it needs to construct transaction inputs for spending. We
-use the simple command-line HTTP client _cURL_ to retrieve the response.
-Note that looking up information using a third-party API like this is similar to
-using a block explorer; see the privacy warning in
-<<block-explorer-privacy>>.
-
-[[example_2-2]]
-.Look up all the unspent outputs for Alice's Bitcoin address
-====
-[source,bash]
-----
-$ address=bc1pyfw56zu5vsq0ulu9kytasgw4xwnm3eysll6tfdz8d9gtht97k7tqxsz78n
-$ curl https://blockchain.info/unspent?active=$address
-----
-====
-
-[source,json]
-----
-{
-  "notice": "",
-  "unspent_outputs": [
-    {
-      "tx_hash_big_endian": "4ac541802679866935a19d4f40728bb89204d0cac90d85f3a51a19278fe33aeb",
-      "tx_hash": "eb3ae38f27191aa5f3850dc9cad00492b88b72404f9da135698679268041c54a",
-      "tx_output_n": 1,
-      "script": "5120225d4d0b946400fe7f85b117d821d533a7b8e490fff4b4b4476950bbacbeb796",
-      "value": 100000,
-      "value_hex": "0186a0",
-      "confirmations": 111,
-      "tx_index": 8276421070086947
-    }
-  ]
-}
-----
-
-The response in <<example_2-2>> shows one unspent output (one that has
-not been redeemed yet) under the ownership of Alice's address.
-The response includes the reference to the transaction in which this
-UTXO is contained (the payment from Joe), the output index
-number, its value in satoshis, and the script derived from Alice's
-address.  With this information, Alice's wallet
-application can construct a transaction to transfer that value to new
-owner addresses.
-
-[TIP]
-====
-View the https://blockstream.info/tx/4ac541802679866935a19d4f40728bb89204d0cac90d85f3a51a19278fe33aeb[transaction from Joe to Alice].
-====
-
 In this case, this single
 UTXO is sufficient to pay for the podcast. Had this not been the case,
 Alice's wallet application might have to combine several
@@ -441,8 +388,8 @@ her funds into two outputs: one to Bob and one back to herself. She can
 then spend the change output in a subsequent transaction.
 
 Finally, for the transaction to be processed by the network in a timely
-fashion, Alice's wallet application will add a small fee. This is not
+fashion, Alice's wallet application will add a small fee. The fee is not
-explicit in the transaction; it is implied by the difference in value between
+explicitly stated in the transaction; it is implied by the difference in value between
 inputs and outputs.  This _transaction fee_ is collected by the
 miner as a fee for validating and including the transaction in a block
 to be recorded on the blockchain.
@@ -489,10 +436,10 @@ connection: wired, WiFi, mobile, etc.  It can also send the transaction
 to another program (such as a block explorer) that will relay it to a
 node.  Her bitcoin wallet does not have
 to be connected to Bob's bitcoin wallet directly and she does not have
-to use the internet connection offered by the cafe, though both those
+to use the internet connection offered by Bob, though both those
 options are possible, too. ((("propagation", "flooding
 technique")))((("flooding technique")))Any Bitcoin node that receives a
-valid transaction it has not seen before will immediately forward it to
+valid transaction it has not seen before will forward it to
 all other nodes to which it is connected, a propagation technique known
 as _gossiping_. Thus, the transaction rapidly propagates out across the
 peer-to-peer network, reaching a large percentage of the nodes within a
@@ -516,7 +463,8 @@ wallet can further verify Alice's transaction only spends valid UTXOs.
 id="MACover02")))((("blockchain (the)", "overview of mining",
 id="BToverview02")))Alice's transaction is now propagated on the Bitcoin
 network. It does not become part of the _blockchain_ until it is
-verified and included in a block by a process called _mining_. See
+included in a block by a process called _mining_ and that block has been
+validated by full nodes. See
 <<mining>> for a detailed explanation.
 
 The Bitcoin system of counterfeit protection is based on computation.
@@ -606,26 +554,26 @@ income from the profits.
 flowing into the network from user wallets and other applications. As
 these are seen by the Bitcoin network nodes, they get added to a
 temporary pool of unverified transactions maintained by each node. As
-miners construct a new block, they add unverified transactions from this
+miners construct a new candidate block, they add unverified transactions from this
-pool to the new block and then attempt to prove the validity of that new
+pool to the candidate block and then attempt to prove the validity of that
-block, with the mining algorithm (Proof-of-Work). The process of mining
+candidate block, with the mining algorithm (Proof-of-Work). The process of mining
 is explained in detail in <<mining>>.
 
-Transactions are added to the new block, prioritized by the highest-fee
+Transactions are added to the new block, prioritized by the highest fee rate
 transactions first and a few other criteria. Each miner starts the
-process of mining a new block of transactions as soon as he receives the
+process of mining a new candidate block of transactions as soon as he receives the
 previous block from the network, knowing he has lost that previous round
-of competition. He immediately creates a new block, fills it with
+of competition. He immediately creates a new candidate block, fills it with
 transactions and the fingerprint of the previous block, and starts
-calculating the Proof-of-Work for the new block. Each miner includes a
+calculating the Proof-of-Work for the candidate block. Each miner includes a
-special transaction in his block, one that pays his own Bitcoin address
+special transaction in his candidate block, one that pays his own Bitcoin address
 the block reward (currently 12.5 newly created bitcoin) plus the sum of
-transaction fees from all the transactions included in the block. If he
+transaction fees from all the transactions included in the candidate block. If he
-finds a solution that makes that block valid, he "wins" this reward
+finds a solution that makes the candidate into a valid block, he "wins" this reward
 because his successful block is added to the global blockchain and the
 reward transaction he included becomes spendable. ((("mining pools",
 "operation of")))Jing, who participates in a mining pool, has set up his
-software to create new blocks that assign the reward to a pool address.
+software to create candidate blocks that assign the reward to a pool address.
 From there, a share of the reward is distributed to Jing and other
 miners in proportion to the amount of work they contributed in the last
 round.
@@ -638,10 +586,11 @@ mining pool. All the miners participating in that mining pool
 immediately start trying to generate a Proof-of-Work for the block template.
 Approximately five minutes after the transaction was first transmitted
 by Alice's wallet, one of Jing's ASIC miners found a solution for the
-block and announced it to the network. After other miners
+block and announced it to the network. After each other miner
-validated the winning block, they started a new lottery to generate the next
+validates the winning block, they start a new lottery to generate the next
 block.
 
+//FIXME:Murch CH2 feedback about most-PoW chain
 Jing's winning block containing Alice's transaction became part of the
 blockchain. The block containing Alice's transaction is counted as one
 "confirmation" of that transaction.  After the block containing Alice's
@@ -719,13 +668,7 @@ committing to it.
 
 Bob can now spend the output from this and other transactions. For
 example, Bob can pay a contractor or supplier by transferring value from
-Alice's podcast payment to these new owners. Bob's bitcoin
+Alice's podcast payment to these new owners.
-software might consolidate many small payments into a larger payment,
-perhaps concentrating all the day's bitcoin revenue into a single
-transaction. This would consolidate the various payments into a single
-output (and a single address). For a diagram of a consolidation
-transaction, see <<transaction-consolidating>>.
-
 As Bob spends the payments received from Alice and other customers, he
 extends the chain of transactions. Let's assume that Bob pays his web
 designer Gopesh((("use cases", "offshore contract services"))) in