NFC
Unlock the phone, hold it to the sticker, done. The chip produces a new checksum on every touch; a copy of the sticker is rejected.
QR code
Phones without NFC scan the QR code on the sticker. In the reports the booking is marked «QR». The location's QR code can also be printed from the Back Office — handy while the sticker is still in the post.
Location check
«I am here» is accepted by the server only if the phone is inside the location zone and the accuracy is under 50 metres. Only «inside / outside» is stored, never a coordinate.
Without internet
An NFC booking is queued on the phone with its signature and device time and sent as soon as there is a connection again (up to 24 hours; the manager sees the note «late sync»). QR code and location check need internet, because the server has to check place and time.
Forgotten
If a booking is missing, the manager adds it under Attendance → Corrections. A reason is mandatory, and the old value stays in the log.
