Site Domain 

The site domain specifies the primary domain of the web site you want to track. For example, your site could have the primary domain yourbusiness.com as well as the subdomains electronics.yourbusiness.com and paperproducts.yourbusiness.com. You should specify the domain without the www prefix.

By default, Webtrends tracks each visitor's traffic across all subdomains. For example, your Webtrends data will show a customer's visit to yourbusiness.com and electronics.yourbusiness.com as the same visit. If you want to track visits to yourbusiness.com, electronics.yourbusiness.com and paperproducts.yourbusiness.com as completely separate visits, then you need to pass the fpcdom config parameter when calling dcs.init().

JavaScript Example:
window.webtrendsAsyncInit = function () {
	var dcs = new Webtrends.dcs();
	dcs.init( {
		dcsid: "dcs9x99xxxx9xxx9xx9xxxx9x_9x9x",
		fpcdom: ".electronics.yourbusiness.com"
	});
	dcs.track();
}