In order to modify the display of the clock in Puppy Linux 4.xx open with a text editor the file:
delete the line:
and substitute with the following line:
<Clock format="%a %d %b %r">minixcal</Clock>
repeat this operation with the file /root/.jwmrc-tray-bak
The result is that you will see the day of the week, the day of the month in figures, the month, the hour and minutes plus the seconds. If you replace %r with %R you will have the military time (0-24 h instead of 0-12 h) but without the seconds.
In order to see the change you have to restart Jwm.