What do Kik message signs mean on Facebook?

The message signs are displayed to give more information about the status of a message. An S with a check mark below it is displayed when the message has been sent to the Kik server.

When the message is delivered to the recipient, a D with a check mark below it appears. An R with a check mark below it is shown when the message is opened and read by the recipient. While the message is in the process of sending, three dots appear, meaning a connection is being established. A red exclamation point means there was an error in which case the message must be sent again. A faded D is displayed when message are sent to iPhones or Windows phones and the recipient has not opened the app to receive the message. Once the app is opened, a solid D appears.