Default [Q] Random Bitmap display In Widget

I have a widget with a few items in it. 1 is a bitmap.

What I would like to do is know if I can randomly show a different one, based on a set timeframe (or even time of day)

I have see the following in advanced parameters, however, it does not seem to change the bitmap... so I'm not sure what to do...

Maybe if you can explain some of the params in it, it would help:

Code:
[ b ]/sdcard/walls/$#Dm#>0?(int((random())*10))$.jpg[ /b ]
I get the math part of it... but I guess what I'm wondering is, what is #Dm#, and what is ? mean...

Does it mean, that every 1 minute, the next random .jpg in the series will show?
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