scope:

This standard identifies, classifies, and defines measures of the software aspects of in-service dependability. As such, it provides a framework for stakeholders to understand the software aspects of dependability and to make dependability measurements throughout the system life cycle.

It provides definitions, requirements, and guidance for the data collection and analysis necessary to make consistent and actionable measurements of a software system's reliability, availability, supportability, and recoverability.

This standard is applicable to any software system or service. It is particularly useful for critical systems where the reliability of their safety, security, functionality, performance, and utilization, as well as recoverability, supportability, and availability are foremost. Examples of critical systems include those supplying communications infrastructure, first responder services, energy production and distribution, real time financial transactions, medical devices, health care administrative services, defense capabilities, personal and mass transportation, environmental monitoring, and water and waste management.

As a catalog of measures, this standard:

a) Defines variables and formulas to quantitatively characterize the software aspects of dependability: reliability, availability, supportability, and recoverability.

b) Presents the in-service reference model (ISRM), a framework for uniform identification of system behaviors and support actions to be measured.

c) Presents the reliability class model to support consistent and extensible differential analysis of the effects of anomalies and failures on the reliability of safety, security, functionality, performance, and utilization.

d) Defines downtime subsets for certain types of activity (slices), providing insight into factors contributing to availability and supportability.

e) Calls for explicit and bounded dependability requirements as a prerequisite for measurement and therefore provides normative criteria and guidance for their development and use.

IEEE Std 1633, Recommended Practice on Software Reliability Engineering [B20] provides a through resource for topics 1 and 2. ISO/IEC/IEEE Std 14764:2022, Software engineering - Software life cycle processes - Maintenance [B25] likewise addresses topic 3.