The storage could not be opened, with $eventData[failReason] saying why. Nothing is persisted
A timer was cancelled by hand
A stored timer was thrown away without running, with $eventData[dropReason] saying why
A timer's code ran: a timeout going off, an interval ticking, or a cron coming round
A timer was put on hold, keeping its record and what was left of its wait
A stored timer was picked back up after a restart, with $eventData[overdueBy] saying how late
A timer on hold was started again, from where its wait was left
Startup finished dealing with every stored timer, counted by $eventData[restored] and $eventData[dropped].
Does not fire at all if the storage could not be opened.
A timer was scheduled
The timer storage opened, and timers will be kept across restarts