In my experience with Webtrends and similar event-logging frameworks the biggest problem with them is that view-related code is mixed up with code responsible for event logging.
It is not so bad when events correspond views directly but unfortunately in my case they are not corresponding, so I end up with bunch of conditions to send particular event.
Do you know any good solution to separate event-logging code from view's code?
The WT.dl parameter is typically used to differentiate pageviews (the page load event should fire WT.dl=0) from on-page events (e.g. downloads, form clicks, etc., which have non-zero values).
When configuring the parameters to send for specific events, make sure to include the WT.dl parameter with a non-zero value that corresponds to the event type. Further reading here:
http://kb.webtrends.com/articles/Information/WT-dl-Values-and-Functionality-1365447872904