Redstone Comparator/DV

A redstone comparator's block data specifies its orientation, mode, and powered status.

Bits	Values
0x1 0x2	A two-bit field storing a value from 0 to 3 specifying the redstone comparator's orientation: 0: Facing north. 1: Facing east. 2: Facing south. 3: Facing west.
0x4	Set if in subtraction mode (front torch up and powered).
0x8	Set if powered (at any power level).