Editing Non-Functional Requirements (section)

== 1. Purpose and Taxonomy ==

Non-functional requirements (NFRs) specify '''how well''' the system must do things, as opposed to '''what''' it must do (functional requirements). They are the quality attributes of the system.

This document uses the '''ISO/IEC 25010:2011 (SQuaRE)''' quality model as its taxonomy. Each NFR is assigned a category from that model:

{|
!width="50%"| ISO 25010 Category
!width="50%"| Subcategories
|-
| '''Performance efficiency'''
| Time behaviour, resource utilisation, capacity
|-
| '''Reliability'''
| Maturity, availability, fault tolerance, recoverability
|-
| '''Security'''
| Confidentiality, integrity, non-repudiation, accountability, authenticity
|-
| '''Maintainability'''
| Modularity, reusability, analysability, modifiability, testability
|-
| '''Portability'''
| Adaptability, installability, replaceability
|-
| '''Operability'''
| Appropriateness recognisability, learnability, user error protection
|-
| '''Compatibility'''
| Co-existence, interoperability
|}

Each NFR entry follows this format:

<pre>NFR-&lt;category&gt;-&lt;NN&gt;
  Requirement:   &lt;measurable statement of what is required&gt;
  Rationale:     &lt;why this matters&gt;
  Test approach: &lt;how it will be verified&gt;
  Priority:      Must Have | Should Have | Nice to Have
  Source:        &lt;observed in code / stakeholder input / best-practice default&gt;
  Status:        [CONFIRMED] | [UNCONFIRMED — needs stakeholder sign-off]</pre>

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<span id="performance"></span>