|description||"Username of the user performing the action"|
|description||"Interface language code of the user doing the actions"|
|description||"Type of the file being acted upon (only for delete, failure, and uploaded, no others)."|
|description||"Detailed error message, only for 'failure' actions."|
|description||"Number of files chosen in a choose or upload action."|
|description||"Action performed by the user.
load is fired when the upload step loads.
choose is fired when a file or a set of files is chosen by the user.
delete is fired when a user deletes a file in the interface.
uploaded is fired when an upload succeeds.
failure is called when an upload fails to complete.
retry is fired when the user retries failed uploads.
continue is fired when the continue button is pressed."|