Webtrends Analytics 9 Adminstration Guide, November 2012
As a best practice, you should define campaigns by tagging your site using the WT.ad and WT.ac Webtrends query parameters, because using this method allows you to create custom reports based on your ad views and ad clicks.
You can use on-site advertising to track visitor activity for the ad views and ad clicks hosted on your site. If you configure on-site advertising using Administration, you can use on-site advertising definitions that you create in profile-level on-site advertising filters.
If you use Webtrends Analytics 9, you configure on-site advertising using Webtrends query parameters rather than using Administration.