Apple iPod touch iOS 6.1 - Manual (Page 51)

Chapter 7 Messages 51
Messages settings
Go to Settings > Messages to set options for Messages, including:
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Turning iMessage on or off
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Notifying others when you’ve read their messages
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Specifying a phone number, Apple ID, or email address to use with Messages
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Showing the Subject field
Manage notifications for messages: See Do Not Disturb and Notifications on page 120.
Set the alert sound for incoming text messages: See Sounds on page 125.