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The vertical blanking interval (VBI) or vertical interval for short is an interval in a television or VDU signal that temporarily suspends transmission of the signal for the electron gun to move back up to the first line of the television screen to trace the next screen field. [1]

The vertical blanking interval can be used to carry data, since anything sent during the VBI would naturally not be displayed. This includes Closed captioning information, which is the context often being discussed with regard to MythTV.