I think I confused my question a bit, but you may have answered indirectly.
The help article I posted says to use the following as a rule for building the pixels:
http://clientname.demdex.net/event?d_event=imp&d_src=datasource_id&d_site=siteID&
d_creative=creative_id&d_adgroup=adgroup_id&d_placement=placement_id
&d_campaign=campaign_id[&d_cid=(GAID|IDFA)%01 DPUUID]&d_bust=cache buster value
What isn't clear to me is what the signal keys will look like from this URL so that I can build Traits. Based on your response, though, the signal keys would be d_creative or d_adgroup from the URL parameters. We'd set up our URLs in the ad platform and look for the appropriate signals to build out traits.
Let me know if I have misunderstood, please.