PVS_SRC_OFFSET:
PVS_SRC_REG_TEMPORARY     = 0 Intermediate storage
PVS_SRC_REG_INPUT         = 1 Input Vertex Storage
PVS_SRC_REG_CONSTANT      = 2 Constant State Storage
PVS_SRC_REG_ALT_TEMPORARY = 3 Alternate Intermediate Storage
PVS_SRC_ADDR_SEL:
PVS_SRC_SELECT_X       = 0 Select X Component
PVS_SRC_SELECT_Y       = 1 Select Y Component
PVS_SRC_SELECT_Z       = 2 Select Z Component
PVS_SRC_SELECT_W       = 3 Select W Component
PVS_SRC_SELECT_FORCE_0 = 4 Force Component to 0.0
PVS_SRC_SELECT_FORCE_1 = 5 Force Component to 1.0
PVS_SRC_ADDR_MODE:
Absolute addressing = 0
Relative addressing using A0 register = 1
Relative addressing using I0 register = 2