I have this URL:
It gets categorized as "Public Information + Social Networking" while http://maps.google.de gets categorized as "Public Information" only.
Although it is in German one can easily reproduce something similar: go to maps.google.de (the classic variant), ask for "hotels nearby wuerzburg" and then try to click on the reviews for one of the hotels. If "Public Information" is alölowed for you but "Social Networking" is not then you get blocked.
I do not understand which mechanism is at work here. Does Web Gateway scan the URL parameters (the part behind "?") too?
How would I formulate a regular expression in a white list?
Whether MWG looks at embedded URLs is controlled under Settings -> URL Filter -> Default in the section Ratings Settings. The second option is Search for and rate embedded URLs. When deselected, the URL that you listed above will show up as Public Information only.
Yes, subdomains might add other categories to an original domain's category.
If you are having problem with this, you could just have a domain whitelist by creating a URL.Host.BelongstoDomains parameter and add maps.google.de to the list you'll create with the rule.
Put this on top of the blocking rule with a 'stop rule set' action.