"have touched upon" is a correct and usable phrase in written English.
It means to briefly mention or discuss a topic or idea. Example: In our meeting yesterday, we touched upon the issue of budget cuts but did not have enough time for a full discussion.
An open question is therefore how the various mechanisms we have touched upon could be better unified to help developers configure, compose, and extend existing platforms, and take informed decisions on how best to obtain desired features.
"Until now," the editor, Earl Martin, writes in the introduction, "only a small number of publications have touched upon aspects of Knoll textile production or have profiled a few of its textile designers".
Mr. President, I have touched upon some of the disarmament issues that remain open and that need to be answered if dossiers are to be closed and confidence is to arise.
Elizabeth Hardwick astutely observed in her review for Harper's, "In certain respects this novel is a representation of some of the ideas about American life, particularly about the Negro in American life, that Baldwin's essays have touched upon.
In all the hours and pages of reportage since rioting returned to our cities last weekend, not one commentator seems to have touched upon the sole unifying factor that fuels and drives such unrest – excitement, fun, teenage kicks.
He might even have touched upon science, and explained that we are all made up of millions of invisible doodads that make us human and also are responsible for that stem-cell thing and for how we choose our leaders.
STEINHARDT -- I don't think we've touched upon what might happen.
Jamie: At the same time, we've touched upon things you're not 'supposed' to touch upon.
We've touched upon some of them in this issue, from the first shave to the first set of wheels.
But having touched upon those ideas, it doesn't develop them with the rigorous wit that Allen might once have brought to bear.
