CzmlDataSource EntityCollection Entity meta data


Please excuse me, this might be a javascript question.
I'm loading some CZML that looks like this at the header:


When this is loaded I can listen for the event and say:
alert( );
and pop-up the name "Vehicle" successfully.

arg2 is instance of Cesium.CzmlDataSource .

Is there a way to read the _comment attribute? We need a flexible way to put meta data into the CZML and process against it at runtime.

(sorry, not a JS programmer, but learning).