My remark above about "Manuel" was unnecessarily snarky. However, the explanation that I and others offered about rNN displaying the number of shots that can be written to the memory buffer is correct. I'm holding a D200 which has Image Quality set to "JPEG Normal." When I half-press the shutter button, the exposure counter display (next to the ISO in the viewfinder) switches to "r25". If I change the Image Quality to Raw+JPEG Normal, a half-press of the shutter shows "r19". If one changes the other image saving settings, the number may change, and of course it also depends on the camera model.