There has to be something somewhere in Cicero …
What I did find, although it is perhaps not an exact match, is this part in Brutus where he talks about orations by Crassus that were preserved in written form and remarks that the record was incomplete:
Plura etiam [sunt] dicta quam scripta, quod ex quibusdam capitibus expositis nec explicatis intellegi potest. Ipsa illa censoria contra Cn. Domitium collegam non est oratio, sed quasi capita rerum et orationis commentarium paulo plenius. Nulla est enim altercatio clamoribus umquam habita maioribus.
Also, more was said than was written down, which can be seen from a number of headers which were put down and then not elaborated. And that censorial speech against his colleague Cn. Domitius is not the speech, but more like a list of headlines and a slightly fleshed-out sketch of the speech. For never has there been a verbal exchange that was conducted under greater clamour.
… or sketchbook, notebook, collection of notes, exposition, however you want to translate commentarium. [I was a bit audacious translating non est oratio as “not the speech” (that was held, that is); other translators prefer something like “not really a speech.” Well, that's what you get for not having articles, Romans!]
So commentarium orationis might carry the meaning of “rough draught” as well.