Dips > Viewing and Display Options
In the Stereonet Options the default projection is a LOWER hemisphere projection. For a horizontal stereonet projection, this means that the plot represents the traces of planes and poles:
on the LOWER half of the sphere, as viewed from ABOVE.
An UPPER hemisphere projection can also be used. This displays the traces of planes and poles:
on the UPPER half of the sphere, when viewed from ABOVE.
An UPPER hemisphere plot is therefore equivalent to a LOWER hemisphere plot rotated by 180 degrees. Use whichever plot you prefer, but be consistent or confusion will result.