The 'TR' mnemonic causes the terminal driver to transmit to the application
all text on the window from the start of the scroll region to the current
cursor position. The transmission is terminated with an ASCII CR (carriage
If graphics mode is on (as set by the 'GS' mnemonic) during any portion of the transmission, then the character transmitted will be preceded by 3 characters describing the color (foreground and background) and the character's attributes. These characters will have the most significant bit set to help distinguish them from text data. Otherwise, the format is the same as specified in the FIN() data for a terminal.
For more information, see Reading The Display.