Prioritising Requirements – How To Do It And Why It Is Critical To Project Success

The MoSCoW rules are employed to help achieve clear prioritisation of requirements. The ‘o’s in the acronym have no meaning. The remaining components of ‘MoSCoW’ as used in this chapter are defined here.

Must have:

These are requirements that are fundamental (they are sometimes also referred to as the ‘minimum usable subset’). Without them, the deliverable will be unworkable and useless. 

Should have:

These are important requirements for which there is a work-around in the short term, or where expectations can be managed. They are things that would have normally have been classified as ‘Must haves’ in a less time-constrained situation, but the deliverable will still be useful and usable without them initially.

Could have:

These are requirements that can more easily be left out at this point. They may well be included in this delivery if their inclusion is easy to achieve without jeopardising the delivery of the ‘Must haves’ and ‘Should haves’. 

Want to have but won’t have this time round (or won’t get yet):

This refers to those valuable requirements that can wait until later. 

This clear definition of terms with precise meanings is significantly better than any prioritisation approach that uses numerical values for priorities, or, even worse, words such as high, medium or low, which do not have a precise meaning outside a specific context.

All of the items in the prioritised requirements list (the MoSCoW list) are due for delivery at some point, although the total delivery may be spread over a number of increments. The MoSCoW rules provide the basis on which decisions can be made regarding the whole project, and during any time boxes included within the project.