REGION
These randoms have not been resolved by the desitarget code. Resolving in this sense means only retaining northern points in northern bricks in the northern portion of the Legacy Surveys footprint and only retaining southern points in the southern bricks in the southern portion. southern bricks in the southern portion of the Legacy Surveys footprint.
REGION
can have the value north
or south
.
See also:
Section 4.1.3. of the desitarget paper.