I am sorry if the docs were unclear. I filed an issue if you could comment on where you got off track building ACIs we will try to have someone in the community fix it up: https://github.com/rkt/rkt/issues/3745
i was worried i was going to go back and look at the docs and see numerous glaring advisories that I'd ignored, having opted instead to read blatantly out of date pages, but no, apart from a few vague parenthetical warnings the docs all talk about building and working with ACIs and the appc spec.