HARVEY MIEI (2018/06/04)
https://developers.ripple.com/checks.html
https://developers.ripple.com/checkcreate.html
https://developers.ripple.com/checkcash.html
https://developers.ripple.com/checkcancel.html
Checks
支票
The Checks feature in the XRP Ledger allows users to create deferred payments that can be canceled or cashed by the intended recipients. Like personal paper checks, XRP Ledger Checks start with the sender of the funds creating a Check that specifies an amount and receiver. The receiver cashes the check to pull the funds from the sender’s account into the receiver’s account. No money moves until the receiver cashes the Check. Because funds are not put on hold when the Check is created, cashing a Check can fail if the sender doesn’t have enough funds when the receiver tries to cash it, just like traditional checks. If there’s a failure cashing the check, the sender can retry until the check expires.
XRP总账网络的Checks支票特性允许用户创建可以被预期接收方取消或兑现的延期付款。与纸质支票一样，XRP总账网络支票由资金发送方创建一张指定额度和接受方的支票。接受方提取支票内的资金，该资金从发送方账户进入接收方账户。在接收方兑现支票之前不会发生任何资金转移。在签发支票时，资金并不会有任何变化。与传统支票一样，发送方账户资金不足会导致接收方支票兑现失败，但在支票过期以前，接收方可以重复兑现操作。
XRP Ledger Checks have expiration times after which they may no longer be cashed. If the receiver doesn’t successfully cash the Check before it expires, the Check object remains in the XRP Ledger until someone cancels it. Anyone may cancel the Check after it expires. Only the sender and receiver can cancel the Check before it expires or is cashed. The Check object is removed from the Ledger when the sender successfully cashes the check or someone cancels it.
XRP总账网络支票在长时间未兑现后则可能会过期。如果接收方在支票过期前未成功兑现，该支票对象将保留在XRP总账网络中直到被人取消。任何人都可以在支票过期后取消支票，只有发送方和接收方可以在支票过期前或兑现前取消支票。支票对象将在接收方成功兑现或有人取消时从总账中移除。
Checks are similar to Escrow and Payment Channels, but there are some important differences between those features and Checks:
You can send issued currency with Checks. With Payment Channels and Escrow, you can only send XRP.
Checks do not tie up any funds. The XRP involved in Payment Channels and Escrow cannot be spent until it is redeemed with a claim provided by the sender (Payment Channels), or released by an expiration or crypto-condition (Escrow).
You can send XRP to yourself through Escrow. You cannot use Checks or Payment Channels to send XRP (or, in the case of Checks, issued currencies) to yourself.
支票与托管和Payment Channels付款渠道相似，但他们之间有一些重要的不同：
用户可以使用支票发送已发行货币，但支付渠道和托管只能发送XRP。
支票不捆绑任何资金。涉及支付渠道和和托管的XRP只有在发送方进行清偿或者托管到期或加密条件释放。
可以以托管方式发送XRP给自己，但不能以支票或付款渠道发送XRP给自己。
Why Checks?
为什么使用支票
Traditional paper checks allow people to transfer balances without immediately exchanging physical currency. XRP Ledger Checks allow people to exchange funds asynchronously using a process that is familiar to and accepted by the banking industry.
传统纸质支票允许用户无需立即兑换实际货币的情况下进行转账付款。XRP总账网络支票允许用户使用近似传统银行支票业务的方式异步处理资金。
XRP Ledger Checks also solve a problem that is unique to the XRP Ledger: they allow users to reject unwanted payments or accept only a portion of a payment. This is useful for institutions that need to be careful about accepting payments for compliance reasons.
XRP总账网络支票也解决了XRP总账网络的唯一问题。允许用户拒绝不想接受的付款或仅接受一部分付款。这对于因合规原因需要小心接受付款的机构很有用。
Checks potentially enable many other use cases. Ripple encourages the community to find new and creative applications for Checks.
Ripple鼓励社区为支票寻找新的和创造性的应用场景。
Use Case: Payment Authorization
案例：付款授权
Problem: To comply with regulations like BSA, KYC, AML, and CFT, financial institutions must provide documentation about the source of funds they receive. Such regulations seek to prevent the illicit transfer of funds by requiring institutions to disclose the source and destination of all payments processed by the institution. Because of the nature of the XRP Ledger, anyone could potentially send XRP (and, under the right circumstances, issued currencies) to an institution’s account on the XRP Ledger. Dealing with such unwanted payments adds significant cost and time delays to these institutions’ compliance departments, including potential fines or penalties.
为遵守像BSA，KYC，AML和CFT这样的规定 ，金融机构必须提供关于他们收到资金来源的文件。 这些法规旨在要求机构披露所有付款的来源和目的地来防止非法转移资金。 由于XRP分类账的性质，任何人都可能将XRP（并且在适当的情况下，已发行货币）发送到XRP分类账的机构账户。 处理这些不必要的支付会给这些机构的合规部门带来巨大的成本和时间延迟，还有可能的罚款或处罚。
Solution: Institutions can enable Deposit Authorization on their XRP Ledger accounts by setting the asfDepositAuth flag in an AccountSet transaction. This makes the account unable to receive Payment transactions. Accounts with Deposit Authorization enabled can only receive funds through Escrow, Payment Channels, or Checks. Checks are the most straightforward, familiar, and flexible way to transfer funds if Deposit Authorization is enabled.
解决方案：机构可以通过其XRP总账网络相关账号发起AccountSet交易并设置asfDepositAuth标志开启付款授权。此后该账号将不能接收付款交易。启用付款授权的账户只能通过托管，付款渠道或者支票接收资金。如果启用付款授权，支票将是最直接，熟悉，灵活的转账方式。
Checks typically have the lifecycle described below.
Step 1: To create a Check, the sender submits a CheckCreate transaction and specifies the receiver (Destination), expiration time (Expiration), and maximum amount that may be debited from the sender’s account (SendMax).
创建支票，发送人提交CheckCreate交易并制定接收人，过期时间，以及可从发送人账户转移的资金额度上限。
Step 2: After the CheckCreate transaction is processed, a Check object is created on the XRP Ledger. This object contains the properties of the Check as defined by the transaction that created it. The object can only be modified by the sender (by canceling it with a CheckCancel transaction) or receiver (by canceling it or cashing it) before the expiration time passes. After the expiration time, anyone may cancel the Check.
当CheckCreate交易处理后，将在XRP总账网络中创建一个Check对象，该对象包含创建交易所定义的支票属性信息。该对象只能被发送人（发起CehckCancel交易取消）或接收人（取消或兑现）在其过期前进行修改。
Step 3: To cash the check, the receiver submits a CheckCash transaction. The receiver has two options for cashing the check:
要兑现支票，接收人提交CheckCash交易，接收人有两个选项兑现支票。
Amount — The receiver can use this option to specify an exact amount to cash. This may be useful for cases where the sender has padded the check to cover possible transfer fees and the receiver can only accept the exact amount on an invoice or other contract.Amount（额度），
DeliverMin — The receiver can use this option to specify the minimum amount they are willing to receive from the Check. If the receiver uses this option, rippled attempts to deliver as much as possible and will deliver at least this amount. The transaction fails if the amount that can be credited to the receiver is not at least this amount.DeliverMin（最小兑现）接收方使用该选项指定其期望从支票中兑现的最小额度。如果接收方使用该选项，则最少兑现指定额度。如果发送方账户的可用额度小于该值，则兑现交易失败。
If the sender has enough funds to cover the Check and the expiration time has not passed, the funds are debited from the sender’s account and credited to the receiver’s account, and the Check object is is destroyed.
如果发送方账户有足够金额足以兑现支票，且支票未过期。资金将从发送方账户转移至接收方账户，同时Check对象将被销毁。
Expiration Case
In the case of expirations, Checks have the lifecycle described below.
All Checks start the same way, so Steps 1 and 2 are the same.
Step 3a: If the Check expires before the receiver can cash it, the Check can no longer be cashed but remains in the ledger.
当接收方在兑现支票时支票已过期，则支票不能被兑现，但仍存在于总账网络中。
Step 4a: After a Check expires, anyone may cancel it by submitting a CheckCancel transaction. That transaction removes the Check from the ledger.
支票过期后，任何人都可以通过提交CheckCancel交易取消支票，支票将在总账网络中被移除。
Availability of Checks
支票可用性
Checks require rippled v0.90.0 or later.