FYI, D.L.Parnas and Barry Boehm defined the field of Software Engineering. Almost all Govt./DoD standards are based on their research and writings.
https://en.wikipedia.org/wiki/Waterfall_model#Modified_water...
Interesting because that's definitely not what's taught in the handful of Software Engineering books I've read, and steps backward are not canon (rather, they're called something besides Waterfall i.e Spiral or Iterative).
Looking at that page again, it looks like what I describe is called "pure waterfall".
Instead of getting lost in the comments, You should post it to HN and invite discussions with a title like "Most of what you have heard about the Waterfall Development Model is Wrong!" or "How the Agile folks have misled you about the Waterfall Development Model" :-)