Thank you for this comment - I'm a physical systems engineer working with software engineers and trying to bridge the gap from a "Systems Engineering" perspecti

Thank you for this comment - I'm a physical systems engineer working with software engineers and trying to bridge the gap from a "Systems Engineering" perspective - where on the HW side we use Functional (what the system should do) and Allocated specifications (how the system is physically architected). I struggle with that bridge - it's largely a terminology mismatch, which is oddly much more difficult than I expected to overcome. Sometimes finding the right words makes all the difference. I'd never heard the term BDUF before. I can see that there's a belief that the BDUF approach implies the design must be perfected before starting to code. I like a healthy concept sketch to use as a roadmap, and evolving accompanying documentation along the way. I use MBSE tools. I certainly would never say a system design is perfected nor are all requirements ever set in stone (under config control - yes, immutable - no). This helps me see where push back is coming from of the SW Dev side.