1.1. 要求表示法和约定

本文档中的关键词 "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY" 和 "OPTIONAL" 只有在以此处所示的全大写形式出现时, 才应按 BCP 14 [RFC2119] [RFC8174] 中的说明进行解释.