How does atd store its job schedule?

On CentOS, scheduled at jobs are clearly stored in /var/spool/at, one file per job. However, what's not clear is where the start times for the jobs are stored. Job file names are a 14 character hex string (e.g. a0000101ac6c40). Is the start time somehow encoded in the file name, or is it stored elsewhere? ETA: By scheduling two jobs one minute apart, it does appear as if the file name contains the start time, but I haven't been able to figure out how to decode it. Anyone know?