====== Reliability Criterion ====== [[public:99_annexes:annex-b-terms-and-definitions:start|Go up to Terms and Definitions]] ===== Discussion ===== A **Reliability Criterion** provides a measurable basis for assessing the [[public:99_annexes:annex-b-terms-and-definitions:r:reliability|Reliability]] of an entity. It identifies a condition against which the performance of a specified function can be evaluated under specified operating conditions and for a specified period of time. A Reliability Criterion may establish a threshold, tolerance, permitted interruption, response time, capacity, error rate, recovery objective, or another measurable condition. The criterion may distinguish required operation, permitted degraded operation, and failed operation. Reliability Criteria may be derived from an applicable [[public:99_annexes:annex-b-terms-and-definitions:r:requirement|Requirement]], [[public:99_annexes:annex-b-terms-and-definitions:p:policy|Policy]], [[public:99_annexes:annex-b-terms-and-definitions:c:constraint|Constraint]], profile, agreement, or decision issued by an [[public:99_annexes:annex-b-terms-and-definitions:a:authority|Authority]]. Each criterion retains its governing source, applicability, identity, [[public:99_annexes:annex-b-terms-and-definitions:v:version|Version]], and [[public:99_annexes:annex-b-terms-and-definitions:p:provenance|Provenance]]. ===== Definition ===== measurable condition used to determine whether an entity performs a specified function under specified conditions for a specified period of time ===== Source ===== Derived for DIDO-TE from [[https://www.iso.org/standard/78176.html|ISO/IEC 25010:2023, Systems and software engineering — Systems and software Quality Requirements and Evaluation (SQuaRE) — Product quality model]], Reliability as a product-quality characteristic; and [[https://www.iso.org/standard/78175.html|ISO/IEC 25002:2024, Systems and software engineering — Systems and software Quality Requirements and Evaluation (SQuaRE) — Quality model overview and usage]], relationships among quality models, measurement, requirement definition, and evaluation ===== Note ===== A Reliability Criterion is the measurable condition used for an assessment. [[public:99_annexes:annex-b-terms-and-definitions:r:reliability|Reliability]] is the quality characteristic being assessed. An operational state is the observed condition of the assessed entity. An operational failure occurs when the entity does not satisfy an applicable Reliability Criterion. A Reliability Criterion does not prescribe a particular monitoring, redundancy, clustering, replication, failover, recovery, or storage mechanism. Those mechanisms are implementation choices unless required by the governing source. When applicable Reliability Criteria conflict, the conflict remains explicit and is referred to the appropriate [[public:99_annexes:annex-b-terms-and-definitions:a:authority|Authority]]. The test environment does not invent precedence among conflicting criteria. ===== Example ===== A Reliability Criterion specifies that a test-control service performs an acknowledged control operation within two seconds under the defined operating load throughout a four-hour Test Execution. The specified function, operating load, response threshold, and duration provide the measurable basis for determining whether the service satisfies the criterion. ---- © 2026 Dido Solutions, Inc. and Jackrabbit Consulting, Inc.