CameraClsMode zbuffer questions

I think this is the right way to go about it... Or am I missing something... If you never clear the z-buffer or backbuffer, they might contain random data...

Graphics3D 800,600,32,2
SetBuffer(BackBuffer())


Cam1 = CreateCamera()
light = CreateLight()

Cube = CreateCube()
PositionEntity(cube,0,0,5)

While Not KeyDown(1)
;TurnEntity cube,1,2,3
PositionEntity(cube,0,0,5)
EntityColor(cube,255,0,0)
CameraClsMode cam1,1,1				
RenderWorld()
EntityColor(cube,255,255,0)
PositionEntity(cube,.5,0,6)
CameraClsMode cam1,0,0				
RenderWorld()
Flip

Wend
End