The creation time and date of the attachment (empty if missing). ISO 8601 format is used : yyyy - mm - ddThh : mm : ss, optionally followed by a timezone : Z, +hh : mm, or - hh : mm. The PDF reference is ambiguous; apparently, the creation time is supposed to be the time and date at which the attachment was the PDF document.Changing the description does not update the modification date / time.

public string getCreationTime()