This field allows us to capture our best ID even when that ID isn't strictly one of the formal taxonomic groups. The field is important because it allows those of us who put effort into trying to ID a specimen to capture what we figure out in a searchable way when we can do better than a formal taxonomic group. This allows us to later come back and refine IDs when we learn more about how to ID these groups in the field. It also allows us to filter out specimens for which we've already made our best guess so we're not constantly re-evaluating them as we scan records to add new IDs. See this article for more information and a list of possible values.