RFC 文档RFC 3168 - The Addition of Explicit Congestion Notification (ECN) to IP2. 约定和缩略语本页总览2. 约定和缩略语2. 约定和缩略语 本文档中出现的关键词 MUST, MUST NOT, REQUIRED, SHALL, SHALL NOT, SHOULD, SHOULD NOT, RECOMMENDED, MAY 和 OPTIONAL 应按 [RFC2119] 中的描述解释.