Software engineers usually understand requirements and testing against requirements. All too often though, those responsible for the safety of a system do not understand how to express requirements which can be understood by engineers, such that the system can be verified. This could be for a myriad reasons, but usually it is due to a gulf between those who are specifying how to determine that a system is safe, and those who are implementing the system.

Subplot demonstrates how stakeholders at all stages of system design and implementation can come together to maintain a document which describes the criteria which, if met, demonstrate compliance with the safety argumentation made about the system. This document can then be rendered as a PDF or some stand-alone HTML for presentation to non-engineer stakeholders for confirmation.

Subplot can also generate a test program, from such a document, that when run will perform all of the verification scenarios contained in the document and produce a final report.

While Subplot is fairly new software, still under active development, the concepts in Subplot are built on those explored in a decade-old previous project, by the same authors, which considered similar problems purely from a software engineering perspective, used a similar Gherkin-inspired language and Markdown input structure, and was used in a variety of projects for paying customers; proving the concept works.

Subplot is a refinement of this older implementation.