Value 1 enables the IR LED, while value 0 disables it. Note that the IR LED will automatically turn off after a certain amount of time if left on this way, however to turn it back on the state has to be set to value zero first. This is set via a GPIO service command, the GPIO module then does the following: it writes 0x10 to 0x10147020 (0x1EC47020 in process space) to enable the LED, and clears that bit to disable it.