<% Day.date %>
return the groupname as formatted date

Sourcecode in Day/macros.js:
1:   function date_macro(param) {
2:      var ts = this.groupname.toDate("yyyyMMdd", this._parent.getTimeZone());
3:      try {
4:         return formatTimestamp(ts, param.format);
5:      } catch (err) {
6:         return "[" + getMessage("error.invalidDatePattern") + "]";
7:      }
8:   }