Abstract: A system of the present invention receives and stores supplemental content for display to an end user upon request. The supplemental content (450) corresponds to a known digital content substrate (410). A unique identifier can be determined via a checksum procedure to identify the known digital content substrate (410). A software routine (404) then assesses an item presented to an end user for display. A candidate identifier can be determined for the display item and matched to the stored unique identifier to identify the display item as the known digital content substrate (410). An interactive indicator symbol (414) can signify availability of supplemental content (450), and uniformly formatted supplemental content (450) can be displayed in a substantially instantaneous manner in response to the user interacting with the interactive indicator symbol (414).