Abstract

The MoSCoW method is used to reach a common understanding with stakeholders on the importance they place on the delivery of each requirement.

The term MoSCoW itself is an acronym derived from the first letter of each of four prioritisation categories: Must Have, Should Have, Could Have, and Won't Have. These words are often capitalized. This document defines these words as they should be interpreted in all design documents.

Design documents published to clients should incorporate the following phrase near the beginning of the document:

‍The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC 2119.

MUST

This word, or the terms REQUIRED or SHALL, mean that the definition is an absolute requirement of the specification.

MUST NOT

This phrase, or the phrase SHALL NOT, mean that the definition is an absolute prohibition of the specification.

SHOULD

This word, or the adjective RECOMMENDED, mean that there may exist valid reasons in particular circumstances to ignore a particular item, but the full implications must be understood and carefully weighed before choosing a different course.

SHOULD NOT

This phrase, or the phrase NOT RECOMMENDED mean that there may exist valid reasons in particular circumstances when the particular behavior is acceptable or even useful, but the full implications should be understood and the case carefully weighed before implementing any behavior described with this label.

MAY

This word, or the adjective OPTIONAL, mean that an item is truly optional. One vendor may choose to include the item because a particular marketplace requires it or because the vendor feels that it enhances the product while another vendor may omit the same item. An implementation which does not include a particular option MUST be prepared to interoperate with another implementation which does include the option, though perhaps with reduced functionality. In the same vein an implementation which does include a particular option MUST be prepared to interoperate with another implementation which does not include the option (except, of course, for the feature the option provides.)