CORE_ATTACHMENT_PROGRESS_PERCENTAGE CORE Endpoint
  /ondemand/core/?method=CORE_ATTACHMENT_PROGRESS_PERCENTAGE  
  Get the progress of a file attachment upload. If attaching one file, NNN will be blank. Otherwise, NNN will indicate each attachment, with 0 being the first  
  RETURN  
  PercentageNNN  
  ProgressNNN Progress Tracking ID
  TotalBytesNNN  
  TransferredBytesNNN