 key words “MUST”, “MUST NOT”, “REQUIRED”, “SHALL”, “SHALL NOT”, “SHOULD”, “SHOULD NOT”, “RECOMMENDED”, “MAY”, and “OPTIONAL”
    in the normative parts of this document
    are to be interpreted as described in RFC 2119.
    However, for readability,
    these words do not appear in all uppercase letters in this specification.

    </p>
   <p>All of the text of this specification is normative
    except sections explicitly marked as non-normative, examples, and notes