[eesmith]

Or from the 1990s, "User manual as spec" - https://archive.org/details/rapiddevelopment00mcco/page/324/...

For example, the Excel Basic spec: https://www.joelonsoftware.com/2006/06/16/my-first-billg-rev...

> Then I sat down to write the Excel Basic spec, a huge document that grew to hundreds of pages. I think it was 500 pages by the time it was done. (“Waterfall,” you snicker; yeah yeah shut up.)

On the page above "user manual as spec" is "point of departure spec", which would be more like the iterative prototyping style.