See qa-plugins/event-logger/qa-event-logger.php, from line 154, function process_event.
params get saved as string with /t delimiter, example:
foreach ($params as $key => $value)
$paramstring.=(strlen($paramstring) ? "\t" : '').$key.'='.$this->value_to_text($value);
See qa-plugins/badges/qa-badge-widget.php, from line 32:
params get read with /t delimiter, example (before comes a mysql request to read params string):
$params = array();
$paramsa = explode("\t",$badge['params']);
foreach($paramsa as $param) {
$parama = explode('=',$param);
$params[$parama[0]]=$parama[1];
}
$slug = $params['badge_slug'];