In the analog age, the device used for this purpose was the watchclock. Watchclocks often had a paper or light cardboard disk placed inside for each 24-hour period. The user would carry the clock to each checkpoint, where a numbered key could be found (typically chained in place). The key would be inserted into the clock where it would imprint the disk. At the end of the shift or 24-hour period an authorized person (usually a supervisor) would unlock the watchclock and retrieve the disk.