以rpc開頭的方法名預留作為系統擴展，且必須不能用于其他地方。每個系統擴展都應該有相關規范文檔，所有系統擴展都應是可選的。 * * * Copyright (C) 2007-2010 by the JSON-RPC Working Group This document and translations of it may be used to implement JSON-RPC, it may be copied and furnished to others, and derivative works that comment on or otherwise explain it or assist in its implementation may be prepared, copied, published and distributed, in whole or in part, without restriction of any kind, provided that the above copyright notice and this paragraph are included on all such copies and derivative works. However, this document itself may not bemodified in any way.