product_name. The label of a metric may contain letters (A-Z, a-z) and underscores.
_cbqobject by providing the key you emailed Chartbeat about, and a value:
&_usr=proto all pings. You can update a Metric at any time during a user's interactions without waiting for them to reload the page or travel to a new page by merely calling
_cbq.pushagain with the same key, and a new value. The change will be reported with the next ping.