This is what I initially thought would be the case.

DBA_SEGMENTS reporting blocks in all allocated extents.
DBA_TABLES reporting the overall usage over time of the blocks in those extents.

Then, of course, I became confused as to why:

BLOCKS (which I believed would be those below HWM) and
EMPTY_BLOCKS (which I believed would be those above HWM)

did not seemingly add up to the total within blocks from all extents.

I looked at various different table segments, from a test (non-changing) environment, immediately after a full analyze.

Is EMPTY_BLOCKS referring to something completely different?

On the other issue, is there any way from the V7 Server to calculate the number of blocks on the freelist, and the avg space available within them (as contained within the V8 DBA_TABLES dictionary view)?