Gap Finder Function - GAP()
The GAP() function has 4 outputs based on the Gap Finder tool:
GapAbove - Price of the beginning of the next gap zone above.
GapBelow - Price of the beginning of the next gap below.
GapAboveSize - the width of the zone above (in $).
GapBelowSize - the width of the zone below (in $).
In this example of $BA the watchlist columns match the zones on the chart:

To scan for when close is currently within 50c of a gap above, and the gap width is greater than $1:
G1 = GAP();
((G1.GapAbove - Close()) < 0.5) and (G1.GapAboveSize > 1)