*Definition [#td0cd8f7]
-Let (X,τ) be a topological space and Y be a [[closed discrete]] collectioin of points of X.  The collction Y is said to be screened if it can be simultaneously separated by disjoint open set.

*Reference [#h3dab5da]
-Willam G. Fleissner, ''On λ collection Hausdorff spaces'', Topology Proceedings 2, (1977, 445-456.