Developers of clinical decision support (CDS) software have their hands full with a recent U.S. FDA final guidance on these products, but the picture promises to become more byzantine with the publication of a draft rule by the Office of the National Coordinator (ONC). The new ONC proposal would require a demonstration of transparency for decision support intervention (DSI) predictive functions in order for that software to qualify for ONC certification, a requirement that might not overlap neatly with the FDA’s own transparency requirements.