what does this engine symbol mean ?

When I analyse my games (or rather just use the full analysis feature on rybka) It sometimes gives the symbol of a half circle does anyone know what this means ?

Which way is the half-circle oriented? Is there a move listed after the symbol, but not just the next move in the game? The book I'm reading now has a half-circle, facing up, as "better is"; aka, move played was not bad but this move is better.

Alternatively, it could be a capital D and that just denotes a diagrammed position at that point;.

it looks like this 

D

but its facing downward

If the flat of the D is on the bottom, it means "Better is".

If the flat of the D is on the top, it means "Worse is".

thanks