Ok, Panopeep, tell us which is which on the D3x ?
Edmund, I was serious. I regularly see posts on different forums stating that the Nikon compression is lossy (and that Sony's CRAW is lossy but not more than Canon 's raw), and the best quality can be achieved by recording the uncompressed data.
Nikon built a tradition of confusion by create either only lossy format (like the D70), or lossy highly compressed vs. lossless slightly compressed version (which they call "uncompressed") with the D100, D200 and D2X. After they decided for a lossless highly compressed version
in addition to the slightly compressed lossless and highly compressed lossy format starting with the D300, the problem arose, how to call these, and they kept the old, incorrect terminology:
uncompressed, meaning lossless, slightly compressed,
compressed, meaning highly compressed, lossy and
lossless compressed, meaning what it says.
To uphold the traditional confusion, the D90 and some others write only losslessly compressed raw data.