OpenAPI-Specification/3.1.0.md at main · OAI/OpenAPI-Specification
Version 3.1.0 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14 RFC2119 RFC8174 when, and only when, they appear in all capitals, as shown here.
https://github.com/OAI/OpenAPI-Specification/blob/main/versions/3.1.0.md
