Fence Line is a Latin figure, used in cha, rumba, and bolero. It is
really a "fencing" body line, and is supposed to be a styalized thrust
with an épée or fencing sword. In rumba, we are usually in butterfly
position. Both dancers cross in front and lunge with a soft knee,
recover, and then step side to face. As you lunge, you can extend your
arms on that side as in a thrust with a sword and raise the other arms
for balance. That is, if you are facing wall and doing the fence line
to reverse with the lead feet, you would thrust with your trail arms,
also to reverse, and raise the lead arms for balance.
In cha both lunge thru with a little thrust with the low hands, recover to face partner, and do a side chassé.
bolero, the first step is often a side step with body rise. Then you
cross the free foot through and lunge on a flexed knee, looking in the
direction of your movement and perhaps giving that little flick with
the leading arms, your thrust with the sword. On the last beat, step
back and turn to face partner.