Using the MoSCoW technique, which priority is given to a requirement which is essential but...

The MoSCoW prioritization technique categorises requirements based on their importance to the current timebox or delivery. The categories are defined as follows:

MUST Have: Non-negotiable; essential for the solution to be viable. If missed, the project fails.

SHOULD Have: Important but not vital; the solution is still viable if these are deferred, but it will be a loss or require a workaround.

COULD Have: Desirable; can be deferred until the next timebox, with a minor impact on value.

WON'T Have this time (or WANT): Agreed not to be delivered now.

The description "essential but which may be deferred in the short term" aligns perfectly with SHOULD Have. This category implies high importance, but the risk of non-delivery is managed through a temporary workaround, making them the first requirements considered for deferral if the schedule is threatened.

(Reference: BCS Requirements Engineering – Prioritisation Techniques, MoSCoW)

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