Use of Imperative Language

Scope

This document defines the use of imperative language across the Implementation Guidance documentation.

The Implementation Guidance is by definition, the individuals’ choice to implement, however in order to increase interoperability with multiple systems, Implementers should follow the recommendations in this Implementation Guidance.

Definition

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED",  "MAY", and "OPTIONAL" in this Guidance are to be interpreted as described in RFC2119 including ERRATA.

Disclaimer

The Implementation Guidance is a best practices information source for Implementers thus usage of MUST/SHALL is not advisable. Instead, SHOULD or RECOMMENDED is to be used, although in some instances the usage of words like REQUIRED will be reasonable to use when imposed by the schema message standard.

However, in the best intent to avoid variances in implementations consequences of not following the recommendation SHOULD be explained and understood.