Version :

%user_name%, %the_real_path%, %the_file_path%, %the_file_name%, %the_file_size%, %the_file_speed%, %the_file_start%, %the_file_end%, %the_file_error%

Enable debug mode to see how the url was called.

If this is for an event where the event happens immediately, and not just on logout, this will only process the most recent item.
Otherwise, it will go through each item executing the command on each.