Would you like to clear something up internally with a coworker before responding to a ticket? The Service-Center offers an 'Internal comment' feature to let you do just that. Open a new ticket and write your note. Click on 'Internal comment' before sending the ticket. The comment will appear in the message history and is shaded gray.
You can also add internal comments to open tickets or tickets that are being processed. Click on 'Internal comment', the text field is now highlighted in gray and is only visible internally. Here you can insert an image or PDF using the paperclip.