This is used by some people for custom field organisation, eg:

{jiraissues:url=http://www.example.com/secure/IssueNavigator.jspa?view=rss&types=2&types=3&types=4&customfield_10030=LCMG%20(044.085)&sorter/field=issuekey&sorter/order=DESC&tempMax=25&reset=true&decorator=none | columns=T;Key;Status;Summary;Assignee;}