... Four digits and three digits are separate camera lines; hence the naming convention used by Nikon...
Did anyone else ever think that Nikon's camera naming conventions are seriously retarded? First the D1 and D100. The lowest segment, the D70, was replaced by the D80 and then the D90. Which is where the D100 should come in logically. But! - difference in number of digits(?) Then what about the D40, D50 and D60? You can't replace those with a D70 anymore (although being half a decade younger, the were arguably more capable), and neither a D90 with a model named D100. Hence the D7000, which is rather correctly to be replaced by a D7100. D400... is that an early D700 predecessor? And how come the top of the shelf stuff has one digit only, the lowliest line (used to have) 2 and the semi professional segment 3?
Can't blame 'em for not being prophetic with their 2012 sales back in 2001 or whatever. It's a sort of historical growth, I know. Still, at one point they should get it together.
Gets even funnier when you compare current/historical Nikon naming with Canon, which is pretty much the inverse. The Canon 40D and the Nikon D40 are not to be mixed up . Neither the Canon 300D ("Digital Rebel") and the Nikon D300.
Sorry for being off topic. ;-) Back to FX.