Gap resistance
This formula plotted on the price chart shows where you might find price support & Resistance if the equity gaps up or down 

A:=If(GapUp()=true,(L-Ref(H,-1))*.5+Ref(H,-1),If( 
GapDown()=true,(Ref(L,-1)-H)*.5+H,PREV)); 
A; 

This formula help in eliminating small gaps 

rng:=Abs(H-L); 
GS:=If(GapUp(),L-Ref(H,-1),If(GapDown(),Ref(L,-1)-H,PREV)); 
A:=If(GapUp()=true AND GS>rng*.75,(L-Ref(H,-1))*.5+Ref(H,-1),If( 
GapDown()=true AND GS>rng*.75,(Ref(L,-1)-H)*.5+H,PREV)); 
A;