Urchin 6 Cross-domain Tracking

Cross-domain traffic is to be used to seamlessly track traffic across two or more top-level domains (two or more sites on the same domain, but with different sub-domains do not need to use cross-domain tracking).
By default, when a user travels from one domain to another, their cookies do not go with them, causing a new session to be generated, even if both sites are reporting to the same log source.

Cross-domain tracking UTM code
Install the following UTM code on all pages in site A and site B, before _trackPageview() or urchinTracker() call, respectively:

ga.js

pageTracker._setDomainName("none");

pageTracker._setAllowLinker(true);

urchin.js

_udn = "none";

_ulink = 1;

When linking from site A to site B
Install the following line of code into the onclick event on site A when linking to site B:

ga.js

pageTracker._link(URL); return false;

urchin.js

_utmLinker(URL); return false;

Alternately, pageTracker._linkByPost(URL) and _utmLinkPost(URL), respectively, may be used to send the necessarily parameters by POST instead of GET.