---
type: "term"
title: "Normative Keywords"
description: "The keywords MUST, MUST NOT, REQUIRED, SHALL, SHALL NOT, SHOULD, SHOULD NOT, RECOMMENDED, MAY, and OPTIONAL in the TLCTC specification are interpreted as described in RFC 2119 / RFC 8174."
resource: "tlctc:term:normative-keywords"
tags:
  - "glossary"
---
# Normative Keywords

The keywords MUST, MUST NOT, REQUIRED, SHALL, SHALL NOT, SHOULD, SHOULD NOT, RECOMMENDED, MAY, and OPTIONAL in the TLCTC specification are interpreted as described in RFC 2119 / RFC 8174. When these keywords appear in lowercase, they carry their ordinary English meaning.

**Reference:** §4.2 (Normative Keywords)