https://developers.ripple.com/autobridging.html
Auto-Bridging
自动桥接
Any OfferCreate that would exchange two non-XRP currencies could potentially use XRP as an intermediary currency in a synthetic order book. This is because of auto-bridging, which serves to improve liquidity across all currency pairs by using XRP as a vehicle currency. This works because of XRP’s nature as a native cryptocurrency to the XRP Ledger. Offer execution can use a combination of direct and auto-bridged offers to achieve the best total exchange rate.
所有OfferCreate交易进行两种非XRP货币的转换潜在都可能以XRP做为中间货币，这就是自动桥接，其通过使用XRP作为承载实现了跨货币交易过程中货币的流通性。这也是XRP作为XRP总账网络内原生加密货币的本质。报价单可以以直接兑换和自动桥接组合的方式实现最佳交易费率。
Example: Anita places an offer to sell GBP and buy BRL. She might find that this uncommon currency market has few offers. There is one offer with a good rate, but it has insufficient quantity to satisfy Anita’s trade. However, both GBP and BRL have active, competitive markets to XRP. Auto-bridging software finds a way to complete Anita’s offer by purchasing XRP with GBP from one trader, then selling the XRP to another trader to buy BRL. Anita automatically gets the best rate possible by combining the small offer in the direct GBP:BRL market with the better composite rates created by pairing GBP:XRP and XRP:BRL offers.
示例：Anita要以英镑兑换巴西雷亚尔，但发现市场上BRL几乎没有报价单。然而英镑和XRP之间，以及巴西雷亚尔和XRP之间，都有大量的交易报价单。自动桥接通过将英镑兑换为XRP，再将XRP兑换为巴西雷亚尔的方式，实现了Anita的目的。且费用低廉。
Auto-bridging happens automatically on any OfferCreate transaction. Payment transactions do not autobridge by default, but path-finding can find paths that have the same effect.
自动桥接自动发生在所有OfferCreate交易中，Payment交易默认不使用自动桥接，但是路径发现功能可以发现具有相同效果的路径。