The NFC attendance solution is an Edusign add-on installed and configured by the Edusign team. Retrieve current-generation NFC tags for the authenticated school, including their GPS coordinates, classroom, signing windows and read-only maximum distance. The tag number filter may return multiple rows because tag numbers are not unique. Signing windows use boundaries relative to the course start and end. One boundary in each array defines one course-wide access interval, including when both margins are zero. Two boundaries in each array define separate access intervals around the course start and course end. Both arrays must have the same length. Boundaries are exclusive. A pair of zero-minute boundaries disables that interval; updates must leave at least one interval enabled. Legacy null margins are returned as zero minutes. Existing configurations with both intervals disabled remain visible so they can be repaired. Malformed signing windows are omitted.