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--- dido:99_annexes:annex-b-terms-and-definitions:m:maintainability [2026/07/11 11:14] – removed - external edit (Unknown date) 127.0.0.1
+++ dido:99_annexes:annex-b-terms-and-definitions:m:maintainability [2026/08/06 10:31] (current) – nick_dido
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+====== Maintainability ======
+[[dido:99_annexes:annex-b-terms-and-definitions:start|Go up to Terms and Definitions]]
+===== Discussion =====
+Maintainability is a [[dido:99_annexes:annex-b-terms-and-definitions:q:quality_characteristic|Quality Characteristic]] concerning the degree to which a subject supports effective and efficient analysis, correction, modification, testing, and controlled change.
+Maintainability applies to subjects such as:
+  * A [[dido:99_annexes:annex-b-terms-and-definitions:c:candidate_solution|Candidate Solution]]
+  * A [[dido:99_annexes:annex-b-terms-and-definitions:d:distributed_system|Distributed System]]
+  * A system
+  * A service
+  * A software component
+  * A [[dido:99_annexes:annex-b-terms-and-definitions:n:node|Node]]
+  * A [[dido:99_annexes:annex-b-terms-and-definitions:q:qualified_node|Qualified Node]]
+  * A [[dido:99_annexes:annex-b-terms-and-definitions:n:node_set|Node Set]]
+  * A governed function implementation
+  * A deployment
+  * A [[dido:99_annexes:annex-b-terms-and-definitions:c:configuration|Configuration]]
+  * Another subject requiring controlled change
+Maintainability concerns activities such as:
+  * Analysis
+  * Diagnosis
+  * Defect correction
+  * Policy update
+  * Configuration change
+  * Interface change
+  * Dependency update
+  * Refactoring
+  * Testing
+  * Regression testing
+  * Controlled release
+  * Version control
+  * Rollback
+  * Retirement of obsolete versions
+Maintainability supports long-term operation, qualification continuity, auditability, evidence continuity, and controlled evolution.
+A Maintainability evaluation can identify:
+  * The evaluated subject
+  * The applicable change
+  * The reason for the change
+  * The affected components
+  * The affected interfaces
+  * The affected dependencies
+  * The applicable [[dido:99_annexes:annex-b-terms-and-definitions:c:configuration|Configuration]]
+  * The applicable [[dido:99_annexes:annex-b-terms-and-definitions:v:version|Version]]
+  * The effort required to analyse the change
+  * The effort required to implement the change
+  * The effort required to test the change
+  * The time required to complete the change
+  * The defects introduced by the change
+  * The applicable regression scope
+  * The applicable rollback procedure
+  * The applicable DIDO [[dido:99_annexes:annex-b-terms-and-definitions:b:baseline|Baseline]]
+  * The applicable [[dido:99_annexes:annex-b-terms-and-definitions:v:validation_criteria|Validation Criteria]]
+  * The applicable [[dido:99_annexes:annex-b-terms-and-definitions:a:acceptance_criteria|Acceptance Criteria]]
+  * Its [[dido:99_annexes:annex-b-terms-and-definitions:e:evidence|Evidence]]
+  * Its [[dido:99_annexes:annex-b-terms-and-definitions:p:provenance|Provenance]]
+  * Its [[dido:99_annexes:annex-b-terms-and-definitions:t:traceability|Traceability]]
+In the Governed Node Service Market, Maintainability supports:
+  * Long-term operation
+  * Qualification continuity
+  * Defect correction
+  * Policy updates
+  * Configuration review
+  * Version control
+  * Auditability
+  * Controlled release
+  * Rollback
+  * Retirement of obsolete implementations
+A maintainable Qualified Node continues to satisfy its governed function obligations after an approved fix, update, configuration change, policy change, interface change, or deployment change.
+Controlled maintenance preserves:
+  * Qualification obligations
+  * Functional obligations
+  * Non-functional obligations
+  * Evidence obligations
+  * Service-level expectations
+  * Interoperability
+  * Traceability
+===== Definition =====
+//[[dido:99_annexes:annex-b-terms-and-definitions:q:quality_characteristic|Quality Characteristic]] concerning the degree to which a subject supports effective and efficient analysis, correction, modification, testing, and controlled change//
+===== Source =====
+Adapted from:
+  * [[https://www.iso.org/standard/78176.html|ISO/IEC 25010:2023, Systems and software Quality Requirements and Evaluation (SQuaRE) — Product quality model]]
+  * Financial Systems Archetype, Part 7: Governed Node Service Market
+  * DIDO Reference Implementation Conceptual Model
+  * DIDO-TE draft Requirements Register
+The original shared definition described Maintainability as the ability of a governed function implementation to support analysis, correction, update, testing, and controlled change.
+This revision generalizes the subject for use throughout the shared DIDO corpus while preserving the original Governed Node Service Market application.
+===== Note =====
+Maintainability supports long-term operation and governance.
+A maintainable Node supports:
+  * Version control
+  * Defect correction
+  * Configuration review
+  * Test Evidence
+  * Controlled release
+  * Rollback
+  * Retirement of obsolete versions
+Maintainability differs from [[dido:99_annexes:annex-b-terms-and-definitions:p:portability|Portability]]:
+  * Portability concerns movement across approved platforms, runtimes, or deployment environments
+  * Maintainability concerns controlled analysis, correction, modification, testing, and change
+Maintainability differs from [[dido:99_annexes:annex-b-terms-and-definitions:r:reliability|Reliability]]:
+  * Reliability concerns the degree to which a subject performs specified functions under specified conditions for a specified period
+  * Maintainability concerns the degree to which the subject supports controlled analysis, correction, modification, testing, and change
+Maintainability differs from [[dido:99_annexes:annex-b-terms-and-definitions:r:recoverability|Recoverability]]:
+  * Recoverability concerns restoration after an interruption or failure
+  * Maintainability concerns controlled changes to the subject and its supporting artifacts
+A maintainable subject does not necessarily require fewer changes. Maintainability concerns the effectiveness, efficiency, control, and verifiability of the change process.
+A Maintainability claim requires identified evaluation conditions. Useful measures include:
+  * Time required to identify a defect
+  * Time required to locate affected components
+  * Time required to implement a correction
+  * Time required to complete regression testing
+  * Number of components affected
+  * Number of defects introduced
+  * Percentage of tests automated
+  * Percentage of changes successfully rolled back
+  * Completeness of change Evidence
+  * Completeness of Traceability
+===== Example =====
+A policy-evaluation Qualified Node receives an approved policy update.
+The provider:
+  * Records the applicable change request
+  * Identifies affected components and interfaces
+  * Updates the implementation
+  * Runs the applicable regression tests
+  * Records the resulting Version and Evidence
+  * Verifies continued satisfaction of the governed function obligations
+  * Releases the updated implementation through the controlled release process
+  * Retains the preceding Version for rollback according to the applicable policy
+The resulting records support evaluation of the Qualified Node's Maintainability.
+In a DIDO-TE evaluation, multiple Candidate Solutions receive the same controlled change request. DIDO-TE compares the analysis effort, implementation effort, testing effort, elapsed time, introduced defects, rollback results, Evidence, and Traceability associated with each Candidate Solution.
+----
+<WRAP centeralign>
+© 2026 Dido Solutions, Inc. and Jackrabbit Consulting, Inc.
+</WRAP>