I do automated trading and use Economic news announcements that are preplanned. FYI, simply the time that the major reports will occur gets input to the trading model. However, it seems that there are revisions to economic news that impacts the market. So when do those occur? Do they only occur as part of the next planned announcement for the report that must be revised? Or can revisions get released at unplanned moments? It appears that they can occur during the next planned report release with some revisions to the previous report. But are other revisions released at unplanned times? Will it be necessary to subscribe to some kind of real time news feed to be privy to each unplanned economic report revisions?