The U.S. FDA’s finalized guidance for clinical decision support (CDS) software was not an entirely isolated policy change inasmuch as there were several other guidances that were edited and reissued two days after the CDS final was published. One of these is the guidance for device software functions and mobile medical apps, which now encodes a transparency requirement as seen in the CDS guidance, a change that may represent a hazard for the unwary medical software developer.