ECProgress is an object describing an operation's state. You should not instantiate one yourself - instead, for all asynchronous operations, one will be returned by the function.
For example, you may encounter:
var progress = ec.checkDeviceStatus();
Integer regarding the internal EC value of operations. -4009 appears to mean "incomplete".
String of the current operation. For the example above, this could be
Description of the current operation. Typically empty. TODO: find how to set a description.
Unknown, typically observed to be 17.
Boolean regarding if this asyncronous operation should be cancelled.
Size currently downloaded. Most useful for a title contents-related operation.
Size of the finished contents. Most useful for a title contents-related operation.
Error code returned from operation.
Information about the error. TODO: find how this is set