2. Notational Conventions (符号约定)

本文档中的关键词 "MUST" (必须), "MUST NOT" (绝对不能), "REQUIRED" (要求), "SHALL" (应), "SHALL NOT" (不应), "SHOULD" (应该), "SHOULD NOT" (不应该), "RECOMMENDED" (推荐), "NOT RECOMMENDED" (不推荐), "MAY" (可以), 和 "OPTIONAL" (可选) 应按 BCP 14 [RFC2119] [RFC8174] 中所述进行解释。