Tunnel <direction>, Tunnel <anything>, Tunnel Thru

From general columns: centers Partner Tag, step ahead, and Trade with each other. Ends Vertical 1/2 Tag into the center, and Quarter in the specified direction. The directions "in" and "out" are relative to the center.

\sxvlines{g2n,g3n,b2s,b1s} \syhlines{b2e,g4w,b3e,g1w}
2 4 3 1 2 4 1 3 2 4 4 2 3 1 1 3
before Tunnel Out after


On Tunnel <anything>, the original ends do the <anything> after their Vertical 1/2 Tag into the center

\sxvlines{g2n,g3n,b2s,b1s} \sxwtees{g1w,b4w,b3n,g4s}
2 4 3 1 2 4 1 3 1 3 4 2 3 1 4 2
before Tunnel Reach Out after


On Tunnel Thru, the Vertical Tag is all the way through, and may be followed by a direction in the usual way.

\sxvlines{g2n,g3n,b2s,b1s} \syhDBDs{b2e,g4e,b1w,g1w}
2 4 3 1 2 4 1 3 2 4 4 2 1 3 1 3
before Tunnel Thru Zig-Zag after