How to add extra attributes to tracked data

General questions
1

Is there any way to add an extra attribute in here, or to change the “label” attribute to a custom value for instance?

{
“label”: “/||localhost:6677…”,
“nb_visits”: 1,
“nb_uniq_visitors”: 1,
“nb_hits”: 1,
“sum_time_spent”: 0,
“nb_hits_with_time_generation”: “1”,
“min_time_generation”: “0.879”,
“max_time_generation”: “0.879”,
“avg_time_on_page”: 0,
“bounce_rate”: “0%”,
“exit_rate”: “0%”,
“avg_time_generation”: 0.879,
“url”: “http:///||localhost:6677…”,
“segment”: “pageUrl==http%…”
},

2

You can add anything you want using the Javascript Tracking API- http://developer.piwik.org/guides/tracking-javascript-guide