Document: NUREG-0800
Document ID: c90016c6-e03f-4224-8ff3-87a6f7d3ca42
Document Type: srp
Title: Appendix 7-A
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0525/ML052500547.pdf
Revision Date: 2023-06
Chapter: 7
Section ID: 7
CFR Part: 
CFR Title: 

Content:
rategy for handling each, the required margins, and the method of measuring those margins. A timing specification should exist for each architectural element, in terms of minimum and maximum times for execution. Scheduling mechanisms and interprocess communication methods should be described. The architecture should be such that operations are performed in the correct sequence. BTP HICB-21 provides additional guidance on real-time performance. SRP Section 7.9 provides additional guidance on digital data communications systems. Software Development Process Characteristics The software development process characteristics that the SAD must exhibit include completeness, consistency, style, traceability, and verifiability. Completeness requires that all the software requirements be satisfied in the architecture. The SAD should address all operating modes specified in the SRS, including initialization, operational, shut-down, maintenance, and test modes. Consistency requires that each software architectural element be compatible with the SRS, the hardware architecture, documented descriptions and known properties of the operational and hardware environment, and other software elements. Timing specifications of each software element should be consistent with the specifications of the other elements with which it interacts and with the expected performance of the system as a whole. Uniform and consistent terminology, notation, and definitions should be used. Style requires that the contents of the SAD be understandable. The architecture description should conform to the developer’s style guide. The architecture specification should contain the rationale for architectural decisions. Traceability requires that a two-way trace exist between the requirements in the SRS and the elements in the architecture. A two-way trace should exist between the architectural elements and the detailed design elements. There should be a forward trace from each architectural element to the