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:
and that no other requirements be stated. The operational environment within which the software will operate should be accurately described. All variables in the physical environment that the software must monitor and control should be properly specified. Functional requirements should accurately describe (1) how each function is initiated; (2) the input and output variables required of the function; (3) the task Appendix 7-A Rev. 4 — June 1997 BTP HICB-14-31 sequences, actions and events required to carry out the function; and (4) the termination conditions and system status at the conclusion of the function. Style requires that the contents of the SRS be understandable. The SRS should differentiate between requirements placed on the software and other supplementary information, such as design constraints, hardware platforms, and coding standards. A precise definition of each technical term should exist, either in the SRS or in a separate dictionary or glossary. Each requirement should be uniquely and completely defined in a single location in the SRS. Traceability requires that a two-way trace exist between each requirement in the SRS, and the safety system requirements and design. There should be a two-way trace between each requirement in the SRS and the software design, as well as a forward trace from each requirement in the SRS to the specific inspections, analyses, or tests used to confirm that the requirement has been met. Unambiguity requires that each requirement, and all requirements taken together, have one and only one interpretation. Verifiability requires that it be possible to construct a specific analysis, review, or test to determine whether each requirement has been met. b. Design Activities & Software Architecture Description A SAD should be produced. The SAD should include all of the functional and software development process characteristics listed below. Functional Characteristics For each of the functional characteristics, the requirements