RM Smartcache filtering

[Jamo]

Hi everyone!

 

I have a query re: filter rules in a Smartcache (which I believe may apply to other filtering solutions too)

 

http://www.alltheweb.com:*cat=img*

 

In an RM article I have noticed the above as an example to filter the image section of alloftheweb.com

 

My question is..... what is that colon doing there!!! I can't seem to find any reference to a colon in the address of the site so I am thinking it has some sort of wildcard function?! Or am I completely wrong (Highly likely!)